#include <bits/stdc++.h>
using namespace std;
const int maxn = 500005;
long long int t, w, b;
long long int gcd(long long int a, long long int b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
int main() {
  int i, j;
  cin >> t >> w >> b;
  long long int temp0 = gcd(w, b);
  long long int x = w / temp0 * b;
  long long int m = min(w, b);
  long long int k = t / x;
  long long int ans;
  double lcm = (double)(w / gcd(w, b)) * (double)b;
  double temp = (double)t;
  if (lcm - temp > 0.001) {
    ans = min(t, m - 1);
  } else {
    ans = m * k;
    ans += min(t % (x), m - 1);
  }
  k = gcd(ans, t);
  printf("%lld/%lld\n", (ans / k), (t / k));
  return 0;
}
