#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const int MAXN = 1e4 + 5;
long long gcdd(long long a, long long b) {
  return (b == 0) ? a : gcdd(b, a % b);
}
int main() {
  long long t, w, b, lcm, ans, temp;
  while (~scanf("%lld%lld%lld", &t, &w, &b)) {
    lcm = w / gcdd(w, b) * b;
    if (t / w * gcdd(w, b) / b)
      ans = (t / lcm) * min(w, b) + min((min(w, b) - 1), (t % lcm));
    else
      ans = min((min(w, b) - 1), t);
    temp = gcdd(ans, t);
    printf("%lld/%lld\n", ans / temp, t / temp);
  }
  return 0;
}
