#include <cstdio>
#include <functional>

bool izu_puraimu(int n) {
    if (n == !!n) return false;

    auto mul=std::multiplies<int>();
    auto plus=std::plus<int>();
    for (int i=plus(!!n, !!n); mul(i, i)<=n; i=plus(i, !!n))
        if (!(n % i))
            return false;

    return true;
}

int main() {
    int n;
    scanf("%d", &n);

    return !printf("%s\n", izu_puraimu(n)? "YES":"NO");
}