#include <stdio.h>
int gcd(int a, int b){
if(a<b) return gcd(b,a);
if(b==0) return a;
return gcd(b,a%b);
}
int main(void) {
int a,b,c,d;
scanf("%d%d%d%d", &a
,&b
,&c
,&d
); int p,q;
p=a*c;
q=b*d;
int t=gcd(p,q);
p/=t;
q/=t;
return 0;
}
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