#include <bits/stdc++.h>
using namespace std;
const int max_int = numeric_limits<int>::max();
unsigned long long gcd(unsigned long long x, unsigned long long y) {
  return y > 0 ? gcd(y, x % y) : x;
}
unsigned long long lcm(unsigned long long x, unsigned long long y) {
  unsigned long long r = x / (x > y ? gcd(x, y) : gcd(y, x));
  return r < 5e18 / y ? r * y : (unsigned long long)5e18 + 1;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  unsigned long long t, w, b;
  cin >> t >> w >> b;
  unsigned long long m = min(w, b);
  unsigned long long s = lcm(w, b);
  unsigned long long r = 0;
  if (s > t) {
    r += min(t, m - 1);
  } else {
    r += t / s * m;
    r += min(t - t / s * s, m - 1);
  }
  unsigned long long q = gcd(t, r);
  cout << r / q << '/' << t / q;
  return 0;
}
