#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return b == 0 ? a : gcd(b, a % b); }
int main() {
  long long t, w, b;
  scanf("%lld", &t), scanf("%lld", &w), scanf("%lld", &b);
  long long GCD = gcd(w, b);
  long long ans;
  if (w * 1.0 / GCD * b > (double)t)
    ans = min(t, min(w - 1, b - 1));
  else {
    long long LCM = w / GCD * b;
    long long num = t / LCM;
    long long remain = t - num * LCM;
    ans = num * min(w, b) + min(remain, min(w - 1, b - 1));
  }
  GCD = gcd(ans, t);
  printf("%lld/%lld\n", ans / GCD, t / GCD);
  return 0;
}
