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