#include <bits/stdc++.h>
using namespace std;
const unsigned long long inf = 5111111111111111111LL;
unsigned long long l, a, b;
unsigned long long gcd(unsigned long long a, unsigned long long b) {
  while (a != 0 && b != 0) {
    unsigned long long k = a;
    a = b;
    b = k % b;
  }
  return a + b;
}
void write(unsigned long long a, unsigned long long b) {
  unsigned long long g = gcd(a, b);
  a /= g;
  b /= g;
  cout << a << "/" << b << endl;
  exit(0);
}
int main() {
  cin >> l >> a >> b;
  unsigned long long g = gcd(a, b);
  unsigned long long nk = a / g;
  if (nk > inf / b + 1) {
    write(min(l, min(a, b) - 1), l);
  }
  nk *= b;
  unsigned long long k = l / nk;
  unsigned long long ans = k * min(a, b);
  k *= nk;
  ans += min(min(a, b), l - k + 1);
  --ans;
  write(ans, l);
  return 0;
}
