C :

#include<stdio.h>
int main()
{
	int a,b,c,d;
	int yue(int x,int y);
	scanf("%d%d%d%d",&a,&b,&c,&d);
	printf("%d\n",yue(a,b));
	printf("%d\n",yue(c,d));
	return 0;
}
int yue(int x,int y)
{
	int i,min,max;
	min=(x>y)?y:x;
	for (i=1;i<min;i++)
	{
		if(x%i==0&&y%i==0)
			max=i;
	}
	return max;
}

C++ :

#include<iostream>
using namespace std;
int main()
{
	int m,n;
	while (cin>>m>>n)
	{
		int r=m%n;
		while (r)
		{
			m=n;
			n=r;
			r=m%n;
		}
		cout<<n<<endl;
	}
	return 0;
}