#include <iostream>
#define ull unsigned long long

using namespace std;

ull gcd(ull a, ull b){
    if (b == 0) return a;
    else return gcd(b, a % b);
}

ull t, w, b;

int main()
{
    cin >> t >> w >> b;
    ull lcm = (w*b) / gcd(w,b);
    ull ans = (t/lcm) * (min(w,b));

    if(w!=b) ans+=min(min(w,b)-1, t);

    ull G = gcd(ans,t);
    cout << (ans/G) << '/' << (t/G) << endl;

    return 0;
}