for_chessus

int main() {
    int t;
    sieve(1000005);
    cin >> t;
    while(t--) {
        int n;
        cin >> n;
        for(int i = 0; i < n; ++i) {
            cin >> nums[i];
        }
        sort(nums, nums+n);

        int ans = -1, j = 1;
        for(int i = 0; i < n; ++i) {
            for(; j < nums[i]; ++j) {
                if(is_prime(j)) {
                    ans = j-1;
                    break;
                }
            }
            j = nums[i] + 1;
            if(ans != -1) break;
        }
        if(ans == -1) {
            while(true) {
                if(is_prime(j)) {
                    ans = j-1;
                    break;
                }
                j++;
            }
        }
        printf("%d\n", ans);
    }
    return 0;
}