#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 n, a, b;
  cin >> n >> a >> b;
  n++;
  long long t = a;
  long long gd = gcd(a, b);
  t /= gd;
  long long ans = n / t;
  ans /= b;
  long long ans1 = ans * min(a, b);
  long long tem = n - ans * t * b;
  ans1 += min(tem, min(a, b));
  ans1--, n--;
  gd = gcd(ans1, n);
  cout << ans1 / gd << "/" << n / gd << endl;
  return 0;
}
