#include <bits/stdc++.h>
using namespace std;
long long int gcd(long long int a, long long int b) {
  long long int mn = min(a, b);
  long long int mx = max(a, b);
  return (!mn) ? mx : (gcd(mx % mn, mn));
}
int main() {
  long long int a, b, c;
  while (cin >> a >> b >> c) {
    long long int mn = min(b, c);
    long long int mx = max(b, c);
    long long int gc = gcd(b, c);
    long long int dv, lc, tot;
    if ((float)mx / gc > a * 1.0 / mn) {
      tot = 0;
      lc = a + 1;
    } else {
      lc = b / gc * c;
      dv = a / lc;
      tot = dv * min(b, c);
    }
    tot += min(a % lc, mn - 1);
    gc = gcd(a, tot);
    cout << tot / gc << "/" << a / gc << endl;
  }
  return 0;
}
