#include <bits/stdc++.h>
using namespace std;

int main() {
    string s; cin >> s;
    bool flag = false;
    for (int i = 0; i < s.size(); i++) {
        if (s[i] != '4' || s[i] != '7') flag = true;
    }
    if (flag) cout << "NO" << endl;
    else cout << "YES" << endl;
}