#include <bits/stdc++.h>
using namespace std;
const int INF = (int)1e9 + 7;
const long long LINF = (long long)1e18 + 9;
const int MXN = (int)1e6 + 10;
const double EPS = (double)1e-9;
long long t, a, b;
long long ans;
long long gcd(long long a, long long b) {
  while (b) {
    a %= b;
    swap(a, b);
  }
  return a;
}
int main() {
  cin >> t >> a >> b;
  if (a > b) swap(a, b);
  long long g = gcd(a, b);
  long long K = 0LL;
  if (a / g <= t / b) {
    K = t / (a / g * b);
  }
  ans += K * a;
  long long l = K * (a / g * b);
  long long r = min(t, l + a - 1);
  ans += (r - l + 1LL);
  long long num = ans - 1LL;
  long long den = t;
  g = gcd(num, den);
  cout << num / g << "/" << den / g;
  return 0;
}
