a和b数组从10001开到现在 仍然还是RE

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n , a[3000001] , b[3000001] , cnt = 0 , t;
    memset ( b , 0 , sizeof ( b ) );
    cin >> n;
    for ( int i = 1 ; i <= n ; i ++ )
        cin >> a[i];
    sort ( a + 1 , a + n + 1 );
    t = ( 10 * a[n] + n );
    for ( int i = 1 ; i <= n ; i ++ )
        b[a[i]] = 1;
    for ( int i = 1 ; i <= a[n] ; i ++ )
        if ( b[i] == 1 )
            cnt ++;
    t += cnt * 5;
    cout << t << endl;
    return 0;
}

求助神犇！