RT，看不出错，打扰了

#include<bits/stdc++.h>
using namespace std;
int main()
{
	long long a,b,c,d,p,q,lcm;
	while(scanf("%lld%lld%lld%lld",&a,&b,&c,&d)!=EOF)
	{
		lcm=b*d/__gcd(b,d);
		a*=lcm/b,c*=lcm/d,b=d=lcm;
		while(c-a>=2)
			a*=2,b*=2,c*=2,d*=2;
		p=a+1,q=b;
		printf("%lld/%lld\n",p,q);
	}
	return 0;
}