#include <bits/stdc++.h>
using namespace std;
long long len, a, b, gcd, bs, ans;
long long GCD(long long a, long long b) {
  long long c;
  while (a % b != 0) {
    c = a % b;
    a = b;
    b = c;
  }
  return b;
}
int main() {
  scanf("%I64d%I64d%I64d", &len, &a, &b);
  gcd = GCD(a, b);
  bs = a / gcd;
  if (log(bs) + log(b) > log(6e18)) {
    ans = min(min(a - 1, b - 1), len);
  } else {
    bs = bs * b;
    ans = (len / bs) * min(a, b) - 1;
    ans += min(len % bs + 1, min(a, b));
  }
  gcd = GCD(ans, len);
  ans /= gcd;
  len /= gcd;
  printf("%I64d/%I64d\n", ans, len);
  return 0;
}
