为什么这一题我WA了（14WA）？

#include <bits/stdc++.h>
#define int long long
using namespace std;

vector<int> primes;

bool is_prime(int x) {
	if (x == 1) return false;
	for (int i = 2; i * i <= x; i++) {
		if (x % i == 0) {
			return false;
		}
	}
	return true;
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(NULL); cout.tie(NULL);
	int n;
	cin >> n;
	for (int i = 1; i <= 100000; i++) {
		if (is_prime(i)) {
			primes.push_back(i);
		}
	}
	int ans = 0;
	for (int i = 0; i < primes.size(); i++) {
		for (int j = i + 1; j < primes.size(); j++) {
			int k = 1ll * primes[i] * primes[j] * primes[j] * primes[j];
			if (k < 1) break;
			if (k <= n) ans++;
		}
	}
	cout << ans << endl;
	return 0;
}