#include <bits/stdc++.h>
using namespace std;
const long double E = 1e-10;
const long long MOD = 1e9 + 7;
long long gcd(long long a, long long b) {
  while (a != 0 && b != 0) a >= b ? a %= b : b %= a;
  return a + b;
}
long long solve_long(long long n, long long a, long long b) {
  long long ans = 0;
  for (long long i = 1; i <= n; i++) {
    if (i / a * a == i / b * b) ans++;
  }
  return ans;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long n, a, b;
  cin >> n >> a >> b;
  long long ans = 0;
  long long A = a;
  ans += min(n, min(a, b) - 1);
  a /= gcd(a, b);
  long long t = n / a;
  t /= b;
  if (t > 1) {
    ans += (t - 1) * min(A, b);
  }
  if (t >= 1) {
    ans += min(n - t * a * b + 1, min(A, b));
  }
  long long r = gcd(n, ans);
  cout << ans / r << "/" << n / r << "\n";
}
