#include <bits/stdc++.h>
using namespace std;
long long gcd(long long x, long long y) {
  while (y) {
    long long r = x % y;
    x = y;
    y = r;
  }
  return x;
}
long long Min(long long a, long long b) {
  if (a > b) return b;
  return a;
}
int main() {
  ios_base::sync_with_stdio(0);
  long long t, w, b;
  cin >> t >> w >> b;
  long long k = gcd(w, b), res;
  double lcm = (double)w * b / k;
  if (lcm > t)
    res = Min(Min(w - 1, b - 1), t);
  else {
    long long res1 = t / lcm;
    res = res1 * Min(w, b) + Min(Min(w - 1, b - 1), t - res1 * lcm);
  }
  k = gcd(res, t);
  cout << res / k << "/" << t / k;
  return 0;
}
