#include <bits/stdc++.h>
using namespace std;
long long int n, m, i, j, k, l, T, u, v, q, t = 0, t1 = 0, te, c = 0;
long long int a[1010], b[1010];
long long int gcd(long long int p, long long int q) {
  if (q == 0)
    return p;
  else
    return gcd(q, p % q);
}
int main() {
  std::ios::sync_with_stdio(false);
  long long int t, w, b;
  cin >> t >> w >> b;
  long long int g = gcd(max(w, b), min(w, b)), lcm, ans = 0;
  double l = w;
  l = l * b;
  l = l / g;
  if (l <= 6e18) {
    lcm = w / g;
    lcm = lcm * b;
    w = min(w, b);
    ans = t / lcm;
    ans = ans * w;
    ans += min(t % lcm, w - 1);
  } else {
    w = min(w, b);
    lcm = t + 1;
    ans += min(t % lcm, w - 1);
  }
  g = gcd(t, ans);
  t = t / g;
  ans = ans / g;
  cout << ans << "/" << t;
}
