algorithms
코드포스 (codeforces)
코드포스 268B (codeforces 268B)
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Problem - 268B - Codeforces
코드
import java.io.*;
public class CF268B {
static int n, ans;
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
ans = n = Integer.parseInt(br.readLine());
for (int i = 1; i < n; i++) {
ans += i * (n - i);
}
bw.write(ans + "\n");
bw.flush();bw.close();
}
}