#include <bits/stdc++.h>
using namespace std;
const int maxn = 100005;
const double eps = 1e-8;
long long t, w, b;
long long gcd(long long aa, long long bb) {
  return !bb ? aa : gcd(bb, aa % bb);
}
int main() {
  while (cin >> t >> w >> b) {
    double lcm = w * 1.0 / gcd(w, b) * b;
    double cntt = 1.0 * t / lcm;
    cntt -= 1;
    long long ans;
    cntt += eps;
    if (cntt >= 0) {
      long long cnt = cntt;
      long long now = w / gcd(w, b) * b;
      long long minn = min(min(w, b), t - (cnt + 1) * now + 1);
      ans = minn;
      long long temp = min(w, b);
      ans += cnt * temp;
      ans += temp - 1;
    } else {
      long long minn = min(w, b);
      ans = min(minn - 1, t);
    }
    long long tt = gcd(t, ans);
    cout << ans / tt << "/" << t / tt << endl;
  }
}
