#include <bits/stdc++.h>
using namespace std;
long long gcd(long long x, long long y) {
  if (!y) return x;
  return gcd(y, x % y);
}
int main(void) {
  long long t, w, b;
  cin >> t >> w >> b;
  long long MIN = min(w, b);
  long long GCD = gcd(w, b);
  double tt = 1.0 * w / GCD * b;
  long long tmp;
  if (tt > 5e18) {
    tmp = min(t, MIN - 1);
  } else {
    long long temp = w / GCD * b;
    MIN--;
    tmp = (t / temp) + (t / temp) * MIN;
    tmp += min(t % temp, MIN);
  }
  GCD = gcd(tmp, t);
  cout << tmp / GCD << '/' << t / GCD << endl;
  return 0;
}
