#include <bits/stdc++.h>
using namespace std;
long long int gcd(long long int a, long long int b) {
  long long int temp;
  if (a < b) {
    temp = a;
    a = b;
    b = temp;
  }
  while (b != 0) {
    temp = a;
    a = b;
    b = temp % b;
  }
  return a;
}
int main() {
  long long int t, w, b;
  scanf("%lld %lld %lld", &t, &w, &b);
  long long G = gcd(w, b);
  long long int lcm = w / G * b;
  long long int p = 0;
  if (w * 1.0 / G * b > (double)t) {
    p = min(t, min(w - 1, b - 1));
  } else
    p = min(w, b) * (t / lcm) + min(t - (t / lcm) * lcm, min(w - 1, b - 1));
  G = gcd(t, p);
  cout << (p / G) << "/" << (t / G) << endl;
  return 0;
}
