CPZT ACGO

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#include <iostream>
using namespace std;
int sushu(int N) {
    int sum = 1;
    if (N < 2) {
        sum = 0;
	}else if (N <= 2 && N > 1) {
        sum = 1;
    }else {
        for (int i = 3;i < N;i++) {
            if (N % i == 0) {
                sum = 0;
                break;
            }
        }
    }
    return sum;
}
int main() {
    int N;
    cin >> N;
    int sum = sushu(N);
    if (sum == 0) {
        cout << "No";
    }else {
        cout << "Yes";
    }
    return 0;
}