HDU 1713 相遇周期

#include <cstdio>
long long gcd(long long a,long long b)
{
if (b==0) return a;
return (gcd(b,a%b));
}

int main()
{
int t;
long long a,b,c,d;
scanf("%d",&t);
while (t--)
{
scanf("%I64d/%I64d%I64d/%I64d",&a,&b,&c,&d);
a=a*b*c*d/gcd(a*d,c*b);
b=b*d;
if(a%b) {c=gcd(a,b); printf("%I64d/%I64d%\n",a/c,b/c);}
else printf("%I64d\n",a/b);
}
return 0;
}