#include <bits/stdc++.h>
using namespace std;
long long int gcd(long long int a, long long int b) {
  return b == 0 ? a : gcd(b, a % b);
}
int main() {
  long long int t, w, b, k = 0;
  scanf("%I64d%I64d%I64d", &t, &w, &b);
  long long int m = min(w, b);
  long long int temp0 = gcd(w, b);
  double lcm = (double)(w / temp0) * (double)b;
  double temp = (double)t;
  if (lcm - temp > 0.01) {
    k = min(t, m - 1);
  } else {
    long long int lcm2 = (w / temp0) * b;
    long long int temp = (t / lcm2);
    k = temp * m;
    k += min(t % (lcm2), m - 1);
  }
  long long int ans = gcd(k, t);
  printf("%I64d/%I64d\n", (k / ans), (t / ans));
  return 0;
}
