#include <bits/stdc++.h>
using namespace std;
unsigned long long gcd(unsigned long long a, unsigned long long b) {
  while (b) {
    a %= b;
    swap(a, b);
  }
  return a;
}
unsigned long long lcm(unsigned long long a, unsigned long long b,
                       unsigned long long t) {
  unsigned long long tmp = (a / gcd(a, b));
  if (t / tmp >= b) return tmp * b;
  return 0;
}
void solve() {
  unsigned long long t, w, b;
  cin >> t >> w >> b;
  unsigned long long tmp1 = lcm(w, b, t);
  unsigned long long z;
  unsigned long long tmp2 = min(w, b) - 1;
  unsigned long long p, q = t;
  z = tmp1;
  if (tmp1 == 0) {
    p = min(tmp2, t);
  } else {
    p = t / z;
    p *= (tmp2 + 1);
    z = min(t % z, tmp2);
    p += z;
  }
  tmp2 = gcd(p, q);
  cout << (p / tmp2) << "/" << (q / tmp2);
}
int main() {
  solve();
  return 0;
}
