#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
int main() {
  long long i, j, k, t, w, b, s, ans = 0;
  double prdt = 1;
  cin >> t >> w >> b;
  long long g = gcd(w, b);
  prdt = (double)w * b;
  long long l = (long long)(prdt / g);
  s = w;
  if (s > b) s = b;
  ans = s * (t / l) - 1 + min(t % l + 1, s);
  long long num = ans;
  long long den = t;
  g = gcd(num, den);
  cout << num / g << "/" << den / g << endl;
  return 0;
}
