ACM ICPC TAIWAN 2016[Problem A] Every Runner is Sometimes Lo

#include<iostream>
#include<string>
#include<cmath>
#include<cstdlib>
#include<fstream>
#include <vector>
using namespace std;

int main()
{
    int c,v1,v2;
    while(cin>>c)
    {
        if(c!=0)
        {
            cin>>v1>>v2;
            int dif=v2-v1;
            if(dif<0)
                dif*=-1;
            dif*=2;
            if(dif==0)
            {
                printf("false\n");
            }
            else if(c%dif==0)
            {
                cout<<c/dif*v1<<endl;
            }
            else
            {
                int x=c,y=dif;
                int tmp;
                while (x % y != 0)
                {
                    tmp = y;
                    y = x % y;
                    x = tmp;
                }
                cout<<c*v1/y<<"/"<<dif/y<<endl;
            }
        }
        else
            break;
    }
}