#include <bits/stdc++.h>
using namespace std;
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  long long int n, a, b, lcm, ans;
  scanf("%lld", &n);
  scanf("%lld", &a);
  scanf("%lld", &b);
  long long int gcc = gcd(a, b);
  if ((n / b) < (a / gcc)) {
    ans = min(min(a, b) - 1, n);
  } else {
    lcm = a * (b / gcc);
    long long int y = n % lcm;
    y = min(y, min(a, b) - 1) + 1;
    ans = (n / lcm - 1) * min(a, b) + y + min(min(a, b) - 1, n);
  }
  long long int gg = gcd(ans, n);
  cout << ans / gg << "/" << n / gg;
  return 0;
}
