#include<stdio.h>
int main()
{
	int m,n,k,p,i,d;
	printf("Input m, n\n");
	scanf("%d%d",&m,&n);
	if(m<n)
	{
		m=m^n;
		n=m^n;
		m=m^n;
	}
	k=0;
	while(!(m&1||n&1)){
	m=(unsigned int)m>>1;
	n=(unsigned int)n>>1;
	k++; 
    }
    for(p=1,i=0;i<k;i++) p=p<<1;
    while((d=m-n)!=n){
    	if(d>n) m=d;
    	else{
    		m=n-d+(n=d);
		}
	}
	d*=p;
	printf("greast common divisor:%d",d);
	return 0;
}