BestCoder#51

#include <cstdio>
#include <iostream>
#include <cmath>
#include <cstring>
using namespace std;
bool visit[10100000];
int prime[10000000];


void init_prim()
{
    memset(visit, true, sizeof(visit));
    int num = 0;
    for (int i = 2; i <= 10000000; ++i)
    {
        if (visit[i] == true)
        {
            num++;
            prime[num] = i;
        }
        for (int j = 1; ((j <= num) && (i * prime[j] <= 10000000));  ++j)
        {
            visit[i * prime[j]] = false;
            if (i % prime[j] == 0) break; 
        }
    }
}
int main() {
    memset(prime, 0, sizeof(prime));
    int T, n;
    init_prim();
    scanf("%d", &T);
    while(T--) {
        scanf("%d", &n);
        bool flag = true;
        if(n < 1e6) {
            if(n == 4) {
                printf("%d
", 2);
            } else if(visit[n] == true){
                printf("%d
", n-1);
            } else {
                printf("%d
", 0);
            }
        } else {
            for(int i = 1; prime[i] <= sqrt(n); ++i) {
                if(n % prime[i] == 0) {
                    flag = false;
                    printf("%d
", 0);
                    break;
                }
            }
            if(flag) {
                printf("%d
", n-1);
            }
        }
    }
    return 0;
}