Jaida vagabunda

#include <bits/stdc++.h>

using namespace std;
bool nums[2000005];

int primes(){
    int i;
    for(i = 2; i <= 2000005; i++){
        if (!nums[i]){
            for(int j = i*i; j <= 2000005; j += i) nums[j] = 0;
        }else return i-1;
    }
    return i;
}

int main(){
    int casos;
    cin >> casos;
    while(casos--){
        memset(nums, 1,sizeof nums);
        int num;
        cin >> num;
        while (num--){
            int aux;
            cin >> aux;
            nums[aux] = 0;
        }
        if (nums[1] != 0) cout << 0 << endl;
        else cout << primes() << endl;
    }
    return 0;
}