#include <bits/stdc++.h>
using namespace std;
long long int hcf1(long long int a, long long int b) {
  if (a == 0)
    return b;
  else
    return hcf1(b % a, a);
  return 0;
}
int main() {
  long long int t, w, b;
  cin >> t >> w >> b;
  long long int to = t;
  long long int hcf = hcf1(w, b);
  long long int lcm = (w / hcf) * b;
  bool check = false;
  if (lcm / w == b / hcf) check = true;
  long long int ans1 = 0;
  if (check == true) {
    long long int k = 1;
    k = t / lcm;
    ans1 = (min(w, b)) * k;
    t = t - lcm * k;
  }
  long long int ans2 = min(min(w, b) - 1, t);
  long long int gcd = hcf1(ans1 + ans2, to);
  cout << (ans1 + ans2) / gcd << "/" << to / gcd;
  cout << "\n";
  return 0;
}
