#include <bits/stdc++.h>
using namespace std;
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long int Lcm(long long int a, long long int b, long long int time) {
  long long int lcm = a / gcd(a, b);
  long long int y = time / lcm;
  if (time % lcm != 0) y++;
  if (b > y) return time + 1;
  return lcm * b;
}
void solve() {
  long long int time, a, b;
  cin >> time >> a >> b;
  long long int lcm = Lcm(a, b, time);
  long long int cnt = time / lcm;
  long long int ans = cnt + cnt * (min(a, b) - 1);
  ans -= min(a, b) - 1;
  long long int y = min(lcm * cnt + min(a, b) - 1, time);
  ans += y - lcm * cnt;
  ans += min(a, b) - 1;
  long long int g = gcd(ans, time);
  cout << (ans / g) << "/" << (time / g) << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
