I/O with cin/cout (unoptimized)

#include <bits/stdc++.h>
using namespace std;

#define N 500000
#define forn(i,n) for (unsigned i = 0; i < n; ++i)

int main(void)
{
    vector<int> v(N);
    forn(i, N) {
    cin >> v[i];
    }
    forn(i, N) {
    cout << v[i] << " ";
    }
}