#include <bits/stdc++.h>
using namespace std;
unsigned long long t, a, b, g, k, mi, ans;
unsigned long long gcd(unsigned long long a, unsigned long long b) {
  if (a % b == 0) return (b);
  return (gcd(b, a % b));
}
int main() {
  scanf("%lld%lld%lld", &t, &a, &b);
  g = gcd(a, b);
  k = t / (a / g) / b;
  mi = min(a, b);
  ans = min(t, mi - 1);
  if (k != 0) {
    ans = ans + (k - 1) * mi;
    ans = ans + min(t - k * (a / g * b) + 1, mi);
  }
  g = gcd(ans, t);
  printf("%lld/%lld\n", ans / g, t / g);
}
