import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;

public class Test4
{
    public static void main(String[]args) throws Exception
    {
        BufferedReader b = new BufferedReader(new InputStreamReader(System.in));
        char[]c = b.readLine().toCharArray();
        Arrays.sort(c);
        c = new StringBuilder(new String(c)).reverse().toString().toCharArray();

        int x = c[0] - c[c.length - 1];
        if(x == 4 || x == 7)
        {
            System.out.println("YES");
        }
        else
        {
            System.out.println("NO");
        }
    }
}