#include <iostream>
using namespace std;
int gcd(int,int);
int gcd(int,int,int,int);
int main()
{
int a,b,g;
cin>>a>>b;
g=gcd(a,b);
cout<<"四个数的最大公约数是"<<g<<endl;
return 0;
}
int gcd(int x,int y)
{
int r;
while (y>0)
{
r=x%y;
x=y;
y=r;
}
return x;
}
int gcd(int x,int y,int z,int m)
{
int g1,g2,h;
g1=gcd(x,y);
g2=gcd(z,m);
h=gcd(g1,g2);
return h;
}