#include <bits/stdc++.h>
using namespace std;
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() {
  long long int gc, ans1, ans2, total1, total2, temp1, temp2, i, L, w, b;
  cin >> L >> w >> b;
  long long int gc1 = gcd(w, b), count = 0;
  if (min(w, b) / gc1 > L / max(w, b))
    count = min(min(w, b) - 1, L);
  else {
    long long int lcf = (w / gc1) * b;
    count += L / lcf;
    count += (count) * (min(w, b) - 1);
    long long int temp = min(L % lcf, min(w, b) - 1);
    count += min(temp, L);
  }
  gc = gcd(count, L);
  ans1 = count / gc;
  ans2 = L / gc;
  cout << ans1 << "/" << ans2;
  return 0;
}
