text: #include<stdio.h>
  int euclid(int x, int y);
  int main(void){
    int a, b;
    printf("a="); scanf("%d",&a);
    printf("b="); scanf("%d",&b);
    printf("gcd(%d, %d)=%d\n", a, b, euclid(a, b));
    return 0;
  }
  int euclid(int x, int y){
    if( x % y == 0 ) return y;
    else return euclid(y, x % y);
  }
  