#include <bits/stdc++.h>
#pragma warning(disable : 4996)
using namespace std;
unsigned long long n, a, b;
unsigned long long gcd(unsigned long long x, unsigned long long y) {
  return x == 0 ? y : gcd(y % x, x);
}
int main() {
  int i, j, k;
  cin >> n >> a >> b;
  if (a > b) swap(a, b);
  unsigned long long g = a / gcd(a, b) * b;
  long double test = (long double)a / gcd(a, b) * b;
  if (test > 5e18) g = n + 1;
  unsigned long long dab = n / g * a - 1 + min(n % g, a - 1) + 1;
  g = gcd(dab, n);
  cout << dab / g << "/" << n / g;
  return 0;
}
