#include <bits/stdc++.h>
using namespace std;
const int INF = (int)1e9 + 7, mod = (int)1e9 + 9, pw = 31, N = (int)1e5 + 123,
          M = (int)1e6 + 123;
const double eps = 1e-11;
const unsigned long long inf = 5e18 + 1;
unsigned long long n, a, b, x, m, ans;
bool check = 0;
unsigned long long binpow(unsigned long long a, unsigned long long b) {
  unsigned long long rec = 0;
  while (b) {
    if (b % 2) {
      rec = rec + a;
      b--;
    } else {
      a = a + a;
      b /= 2;
    }
    if (rec > n || a > n) {
      check = 1;
      return 0;
    }
  }
  return rec;
}
long long gcd(long long x, long long y) { return (y ? gcd(y, x % y) : x); }
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cin >> n >> a >> b;
  ans = min(n, min(a, b) - 1);
  m = binpow(a, b / gcd(a, b));
  if (check) {
    cout << ans / gcd(ans, n) << "/" << n / gcd(ans, n);
    return 0;
  }
  ans += ((n / m) - 1) * min(a, b);
  ans += min((n / m) * m + min(a, b) - 1, n) - (n / m) * m + 1;
  cout << ans / gcd(ans, n) << "/" << n / gcd(ans, n);
  return 0;
}
