5.20

#include<stdio.h>
main(){
int m,n,temp,i;
printf("Input m&n:");
scanf("%d%d",&m,&n);
if(m<n){
temp=m;
m=n;
n=temp;}
for(i=n;i>0;i--)
if(m%i==0&&n%i==0)
{
printf("The GCD of %d and %d is: %d\n",m,n,i);
break;
}}