#include <bits/stdc++.h>
using namespace std;
long long t, w, b;
long long gcd(long long m, long long n) {
  if (n == 0)
    return m;
  else
    return gcd(n, m % n);
}
int main() {
  scanf("%I64d%I64d%I64d", &t, &w, &b);
  if (w < b) {
    long long a = w;
    w = b;
    b = a;
  }
  long long c = t / (w / gcd(w, b)) / b;
  long long num = b - 1;
  long long count = min(b - 1, t - c * b * (w / gcd(w, b)));
  long long ans;
  if (b != 1)
    ans = c * num + count + c;
  else
    ans = c + count;
  long long a = gcd(ans, t);
  ans = ans / a;
  t = t / a;
  printf("%I64d/%I64d\n", ans, t);
  return 0;
}
