#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
const long long int inf = 1e16;
long long int t, r, g, ans;
long long int gcd(long long int a, long long int b) {
  return b ? gcd(b, a % b) : a;
}
int main() {
  while (~scanf("%lld%lld%lld", &t, &r, &g)) {
    if (g > r) swap(g, r);
    long long int q = r / gcd(r, g) * g;
    if ((long double)r / gcd(r, g) > (long double)t / g)
      ans = ((t) < (g - 1) ? (t) : (g - 1));
    else {
      long long int x = t / q;
      ans = x * g + g - 1;
      long long int m = x * q;
      ans -= (((long long int)0) > (m + g - 1 - t) ? ((long long int)0)
                                                   : (m + g - 1 - t));
    }
    long long int k = gcd(t, ans);
    t /= k;
    ans /= k;
    printf("%lld/%lld\n", ans, t);
  }
  return 0;
}
