#include <bits/stdc++.h>
using namespace std;
unsigned long long t;
unsigned long long w;
unsigned long long b;
template <typename T>
T commonDivisor(T a, T b) {
  while (true) {
    T c = a % b;
    if (!c) break;
    a = b;
    b = c;
  }
  return b;
}
template <typename T>
T commonMutiple(T a, T b) {
  return a * (b / commonDivisor(a, b));
}
unsigned long long algo1() {
  unsigned long long p = 0;
  for (unsigned long long i = 1; i <= t; ++i) {
    if (i % w == i % b) ++p;
  }
  return p;
}
unsigned long long algo2() {
  unsigned long long tie = 0;
  for (unsigned long long i = 0; i < t / w; ++i) {
    if (!(i * w % b)) {
      tie += b;
    }
  }
  if (!(w * (t / w) % b)) {
    tie += min(t % w + 1, b);
  }
  return tie - 1;
}
unsigned long long algo3() {
  unsigned long long tie;
  unsigned long long d = commonDivisor(w, b);
  if (w / d <= t / b) {
    unsigned long long m = w / d * b;
    tie = b * (t / m) + min(t - (t / m) * m + 1, b) - 1;
  } else {
    tie = min(t + 1, b) - 1;
  }
  return tie;
}
int main() {
  cin >> t >> w >> b;
  if (w < b) swap(w, b);
  unsigned long long tie = algo3();
  unsigned long long d = commonDivisor(tie, t);
  cout << tie / d << '/' << t / d;
  return 0;
}
