#include <bits/stdc++.h>
const double EPS = 1e-24;
const long long int MOD = 1000000007ll;
const double PI = 3.14159265359;
long long int INF = 6e18;
template <class T>
T Max2(T a, T b) {
  return a < b ? b : a;
}
template <class T>
T Min2(T a, T b) {
  return a < b ? a : b;
}
template <class T>
T Max3(T a, T b, T c) {
  return Max2(Max2(a, b), c);
}
template <class T>
T Min3(T a, T b, T c) {
  return Min2(Min2(a, b), c);
}
template <class T>
T Max4(T a, T b, T c, T d) {
  return Max2(Max2(a, b), Max2(c, d));
}
template <class T>
T Min4(T a, T b, T c, T d) {
  return Min2(Min2(a, b), Max2(c, d));
}
using namespace std;
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  a %= b;
  return gcd(b, a);
}
long long int lcm(long long int a, long long int b) {
  long long int g = gcd(a, b);
  a /= g;
  if (a * b / b != a) return INF;
  return a * b;
}
int main() {
  std::ios::sync_with_stdio(false);
  cin.tie(0);
  long long int t, a, b;
  cin >> t >> a >> b;
  long long int tt = t;
  long long int LCM = lcm(a, b);
  long long int L = min(a, b) - 1;
  long long int ans = 0;
  ans += t / LCM * (L + 1);
  t %= LCM;
  ans += min(t, L);
  long long int GCD = gcd(ans, tt);
  cout << ans / GCD << "/" << tt / GCD << endl;
}
