1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));

        Long n = Long.parseLong(br.readLine().trim());

        if (isPrime(n)) {
            out.println("Yes");
        } else {
            out.println("No");
        }

        out.flush();
        out.close();
        br.close();
    }

    private static boolean isPrime(long n) {
        if (n == 1) {
            return false;
        }

        for (long i = 2; i * i <= n; i++) {
            if (n % i == 0) {
                return false;
            }
        }
        return true;
    }