#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100000 + 5;
int n, q;
vector<int> e[MAXN];
int init_color[MAXN]; // 初始颜色
int ans[MAXN];        // 最终答案
// 每个点的：父节点、深度、大小、重子节点
int fa[MAXN], dep[MAXN], siz[MAXN], hson[MAXN];
void dfs_build(int u, int fat)
{
    hson[u] = 0;
    siz[u] = 1;
    for (int i = 0; i < e[u].size(); i++)
    {
        int v = e[u][i];
        if (v == fat)
            continue;
        dep[v] = dep[u] + 1;
        fa[v] = u;
        dfs_build(v, u);
        siz[u] += siz[v];
        if (siz[v] > siz[hson[u]])
            hson[u] = v;
    }
}
// 每个点的：所在链的链顶、重边优先的 dfs 序、dfs序对应的节点编号
int tot, top[MAXN], dfn[MAXN], rnk[MAXN];
void dfs_div(int u, int fa)
{
    dfn[u] = ++tot;
    rnk[tot] = u;
    if (hson[u])
    {
        top[hson[u]] = top[u];
        dfs_div(hson[u], u);
        for (int i = 0; i < e[u].size(); i++)
        {
            int v = e[u][i];
            if (v == fa || v == hson[u])
                continue;
            top[v] = v;
            dfs_div(v, u);
        }
    }
}
struct Res
{
    // 左边颜色，右边颜色，颜色段数
    int lcolor, rcolor, sum;
};
struct SegTree
{
    int sum[4 * MAXN];    // 有多少段颜色
    int lazy[4 * MAXN];   // 延迟染色，0 表示没有染色
    int lcolor[4 * MAXN]; // 区间左端点颜色
    int rcolor[4 * MAXN]; // 区间右端点颜色
    void up(int now)
    {
        sum[now] = sum[now * 2] + sum[now * 2 + 1];
        lcolor[now] = lcolor[now * 2];
        rcolor[now] = rcolor[now * 2 + 1];
        if (rcolor[now * 2] == lcolor[now * 2 + 1])
            sum[now]--;
    }
    void down(int now, int l, int r)
    {
        if (l == r || lazy[now] == 0)
            return;
        sum[now * 2] = 1;
        sum[now * 2 + 1] = 1;
        lazy[now * 2] = lazy[now];
        lcolor[now * 2] = lazy[now];
        rcolor[now * 2] = lazy[now];
        lazy[now * 2 + 1] = lazy[now];
        lcolor[now * 2 + 1] = lazy[now];
        rcolor[now * 2 + 1] = lazy[now];
        lazy[now] = 0;
    }
    void build(int now, int l, int r)
    {
        lazy[now] = 0;
        if (l == r)
        {
            sum[now] = 1;
            lcolor[now] = rcolor[now] = init_color[rnk[l]];
            return;
        }
        int mid = (l + r) / 2;
        build(now * 2, l, mid);
        build(now * 2 + 1, mid + 1, r);
        up(now);
    }
    // x~y 染成 z 色
    void update(int now, int l, int r, int x, int y, int z)
    {
        if (x <= l && r <= y)
        {
            sum[now] = 1;
            lcolor[now] = rcolor[now] = z;
            lazy[now] = z;
            return;
        }
        down(now, l, r);
        int mid = (l + r) / 2;
        if (x <= mid)
            update(now * 2, l, mid, x, y, z);
        if (y >= mid + 1)
            update(now * 2 + 1, mid + 1, r, x, y, z);
        up(now);
    }
    Res query(int now, int l, int r, int x, int y)
    {
        if (x <= l && r <= y)
            return (Res){lcolor[now], rcolor[now], sum[now]};
        down(now, l, r);
        int mid = (l + r) / 2;
        Res res = {0, 0, 0};
        Res lRes = {0, 0, 0};
        Res rRes = {0, 0, 0};
        if (x <= mid)
        {
            lRes = query(now * 2, l, mid, x, y);
            res = lRes;
        }
        if (y >= mid + 1)
        {
            rRes = query(now * 2 + 1, mid + 1, r, x, y);
            if (res.lcolor == 0)
                res.lcolor = rRes.lcolor;
            res.rcolor = rRes.rcolor;
            res.sum += rRes.sum;
        }
        // 左右都有涉及，并且中间颜色一样，段数就少一段
        if (lRes.sum > 0 && rRes.sum > 0 && lRes.rcolor == rRes.lcolor)
            res.sum--;
        return res;
    }
} st;
// u~v路径上查询颜色段数
int query(int u, int v)
{
    int res = 0;
    int ulast = -1; // u上一段最后的颜色
    int vlast = -1; // v上一段最后的颜色
    while (top[u] != top[v])
    {
        if (dep[top[u]] < dep[top[v]])
        {
            // v~top[v] 计入答案中
            Res now = st.query(1, 1, tot, dfn[top[v]], dfn[v]);
            res += now.sum;
            if (now.rcolor == vlast)
                res--;
            vlast = now.lcolor;
            v = fa[top[v]];
        }
        else
        {
            // u~top[u] 计入答案中
            Res now = st.query(1, 1, tot, dfn[top[u]], dfn[u]);
            res += now.sum;
            if (now.rcolor == ulast)
                res--;
            ulast = now.lcolor;
            u = fa[top[u]];
        }
    }
    if (dep[u] > dep[v])
    {
        swap(u, v);
        swap(ulast, vlast);
    }
    Res now = st.query(1, 1, tot, dfn[u], dfn[v]);
    res += now.sum;
    if (now.lcolor == ulast)
        res--;
    if (now.rcolor == vlast)
        res--;
    return max(res, 1);
}

void update(int u, int v, int z)
{
    while (top[u] != top[v])
    {
        if (dep[top[u]] < dep[top[v]])
        {
            // v~top[v] 计入答案中
            st.update(1, 1, tot, dfn[top[v]], dfn[v], z);
            v = fa[top[v]];
        }
        else
        {
            // u~top[u] 计入答案中
            st.update(1, 1, tot, dfn[top[u]], dfn[u],z);
            u = fa[top[u]];
        }
    }
    if (dep[u] > dep[v])
        swap(u, v);
    st.update(1, 1, tot, dfn[u], dfn[v],z);
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> q;
    for (int i = 1; i <= n; i++)
        cin >> init_color[i];
    for (int i = 1; i <= n - 1; i++)
    {
        int u, v;
        cin >> u >> v;
        e[u].push_back(v);
        e[v].push_back(u);
    }
    dep[1] = 1;
    fa[1] = 0;
    dfs_build(1, 0);
    tot = 0;
    top[1] = 1;
    dfs_div(1, 0);
    /*
    for(int i=1;i<=tot;i++)
        cout<<dfn[i]<<" ";
    cout<<endl;
    */
    //--------
    st.build(1, 1, tot);
    while (q--)
    {
        char op;
        int a, b, c;
        cin >> op;
        if (op == 'C')
        {
            cin >> a >> b >> c;
            update(a, b, c);
        }
        else if (op == 'Q')
        {
            cin >> a >> b;
            cout << query(a, b) << "\n";
        }
    }
    return 0;
}