#include <bits/stdc++.h>
using namespace std;
long long gcd(long long x, long long y) { return y == 0 ? x : gcd(y, x % y); }
long long t, a, b, aa, bb, g;
long long ab, mi;
long long get() {
  if (t / aa < bb) return 0;
  ab = aa * bb;
  if (t / ab < g) return 0;
  long long abg = ab * g;
  long long re = t / abg - 1;
  long long yu = t % abg;
  cerr << "re"
       << " <- " << re << endl;
  return re * mi + min(mi, yu + 1);
}
int main() {
  cin >> t >> a >> b;
  mi = min(b, a);
  g = gcd(a, b);
  aa = a / g;
  bb = b / g;
  long long ans = min(mi - 1, t);
  ans += get();
  long long gg = gcd(ans, t);
  printf("%I64d/%I64d\n", ans / gg, t / gg);
  return 0;
}
