https://www.acmicpc.net/problem/23812
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#define fastio ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define int int64_t
using namespace std;
char DB[5][6] = {
"@ @",
"@@@@@",
"@ @",
"@@@@@",
"@ @",
};
int32_t main(){
fastio;
int n; cin >> n;
const int sz = 5*n;
for(int i = 0; i < sz; i++,puts(""))
for(int j = 0; j < sz; j++)putchar(DB[i/n][j/n]);
}