#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return (b == 0 ? a : gcd(b, a % b)); }
int main() {
  long long t, a, b;
  cin >> t >> a >> b;
  long long mx = t / a;
  long long g = gcd(a, b);
  long long m = b / g;
  long long tie = min(t, min(a - 1, b - 1));
  long long res;
  if (m > mx) {
    res = tie;
  } else {
    long long lcm = a * m;
    res = (t / lcm) * (tie + 1) + tie;
    res -= max(0ll, lcm * (t / lcm) + tie - t);
  }
  long long g2 = gcd(res, t);
  cout << res / g2 << "/" << t / g2 << endl;
}
