#include <bits/stdc++.h>
using namespace std;
long long t, w, b;
long long gcd(long long a, long long b) { return b == 0 ? a : gcd(b, a % b); }
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
int check(long long a, long long b, long long c) {
  if (log(a * 1.0) + log(b * 1.0) - log(gcd(a, b) * 1.0) > log(c * 1.0))
    return 1;
  return 0;
}
int main() {
  cin >> t >> w >> b;
  if (w == b) {
    printf("1/1");
    return 0;
  }
  long long ans1, ans2 = t;
  if (check(w, b, t)) {
    ans1 = min(w - 1, min(b - 1, t));
  } else {
    long long kkk = lcm(w, b);
    long long ggg = t / kkk;
    long long Ans1;
    if (ggg * kkk + min(w, b) <= t)
      Ans1 = (ggg + 1) * min(w, b) - 1;
    else
      Ans1 = ggg * (min(w, b) - kkk) + t;
    ans1 = Ans1;
  }
  printf("%lld/%lld", ans1 / gcd(ans1, ans2), ans2 / gcd(ans1, ans2));
}
