Project Euler 007

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e7 + 10;

int tot;
int ntp[N];
int primes[N];

void sieve () {
	ntp[1] = 1;
	for(int i = 2;i < N; i ++) {
		if(!ntp[i]) {
			primes[++tot] = i;
		}
		for(int j = 1;j <= tot and i * primes[j] < N; j ++) {
			ntp[i * primes[j]] = 1;
			if(i % primes[j] == 0) break;
		}
	}
}

signed main () {
	sieve();
	cout << primes[10001] << endl;
	return 0;
}