#include <bits/stdc++.h>
using namespace std;
long long multi(long long a, long long b) {
  if (b == 0) return 0;
  long long temp = multi(a, b / 2);
  unsigned long long t = temp + temp;
  if (t > 5000000000000000000ull) {
    return -1;
  }
  if (temp == -1) return -1;
  if (b % 2 == 1) {
    t += a;
  }
  if (temp > 5000000000000000000ll) {
    return -1;
  }
  return t;
}
long long gcd(long long a, long long b) {
  if (b == 0) {
    return a;
  }
  return gcd(b, a % b);
}
int main() {
  long long t, w, b;
  cin >> t >> w >> b;
  long long t2 = min(w, b);
  long long t1 = w / gcd(w, b);
  t1 = multi(t1, b);
  long long ans = 0;
  long long t3 = t;
  if (t1 != -1) {
    ans += (t / t1) * t2;
    t3 %= t1;
  }
  ans += min(t2, t3);
  ans--;
  if ((t % w) == (t % b)) ans++;
  long long temp = gcd(ans, t);
  cout << ans / temp << "/" << t / temp;
  return 0;
}
