#include <bits/stdc++.h>
using namespace std;
long long T, W, B, H, P;
long long fpb(long long A, long long B) {
  if (A == 0) {
    return B;
  }
  return fpb(B % A, A);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> T >> W >> B;
  H = W / fpb(W, B);
  if (T / B < H) {
    P = min(W, B) - 1 - max((long long)0, min(W, B) - 1 - T);
  } else {
    H *= B;
    P = (T / H + 1) * min(W, B) - 1 - max((long long)0, min(W, B) - 1 - T % H);
  }
  H = fpb(P, T);
  cout << P / H << '/' << T / H << '\n';
}
