40pt

def gcd(a,b):
    if b==0:
        return a
    return gcd(b,a%b)

a=int(input())
b=int(input())
print(gcd(a,b))

100pt

def gcd(a,b):
    cnt2 = 0
    while a != b:
        if a < b:
            a, b = b, a
        aEven = (a % 2 == 0)
        bEven = (b % 2 == 0)
        if aEven and not bEven:
            a = a // 2
        elif not aEven and bEven:
            b = b // 2
        elif aEven and bEven:
            cnt2 += 1
            a = a // 2
            b = b // 2
        else:
            a = a - b
    while cnt2 > 0:
        a = a * 2
        cnt2 -= 1
    return a
a=int(input())
b=int(input())
print(gcd(a,b))

C++ 正解

#include<bits/stdc++.h>
//#define int long long
using namespace std;
int cnt,re;

struct Bignum{
	int num[10005],len;
};
Bignum c;
inline void write(int N){
	if (N < 0){
		putchar('-');
		N = -N;
	}
	if (N >= 10){
		write(N / 10);
	}
	putchar(N % 10 + '0');
}
void read(Bignum &a) 
{
	string s;
	cin>>s;
	int l=s.size();a.len=l;
	for(int i=0;i<l;i++)a.num[l-i]=s[i]-'0';
}

int compare(Bignum &a,Bignum &b)
{
	if(a.len!=b.len)return a.len<b.len;
	for(int i=a.len;i>0;i--)
	{
		if(a.num[i]!=b.num[i])return a.num[i]<b.num[i];
	}
	return 2;
}

int pd(Bignum &a){return a.num[1]%2;}

void chu(Bignum &a)
{
	re=0;
	for(int i=a.len;i>=1;i--)
	{
		a.num[i]+=10*re;
		re=a.num[i]%2;
		a.num[i]/=2;
		if(i==a.len&&a.num[i]==0)a.len--;
	}
}

void cut(Bignum &a,Bignum &b)
{
	for(int i=a.len;i>=1;i--)
	{
		a.num[i]-=b.num[i];
		if(a.num[i]<0)
		{
			for(int j=i+1;a.num[j-1]<0;j++)
			{
				a.num[j]--;
				a.num[j-1]+=10;
			}
		}
	}
	for(int i=a.len;i>=1;i--)
	{
		if(a.num[i]!=0)break;
		a.len--;
	}
}

void mu(Bignum &a)
{
	re=0;
	for(int i=1;i<=a.len;i++)
	{
		a.num[i]*=2;
		a.num[i]+=re;
		re=0;
		if(a.num[i]>=10)re=a.num[i]/10,a.num[i]%=10;
	}
	if(re)a.num[++a.len]=re;
}

void out(Bignum &a)
{
	for(int i=a.len;i>=1;i--)write(a.num[i]);
}

void gcd(Bignum &a,Bignum &b)
{
	cnt=0;
	while(compare(a,b)!=2)
	{
		if(compare(a,b)==1)
		{
			c=a;
			a=b;
			b=c;
		}
		int a1=pd(a),b1=pd(b);
		if(!pd(a)&&pd(b))chu(a);
		else if(pd(a)&&!pd(b))chu(b);
		else if(!pd(a)&&!pd(b))cnt++,chu(a),chu(b);
		else cut(a,b);
	}
	while(cnt--)mu(a);
}

signed main()
{
	Bignum a,b;
	read(a);read(b);
    gcd(a,b);
	out(a);
	return 0;
}