18 lines
431 B
Java
18 lines
431 B
Java
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import java.util.Scanner;
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public class Main {
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static long[] f = new long[2000001];
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public static void main(String[] args) {
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Scanner reader = new Scanner(System.in);
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String s = reader.next();
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int c=0;
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for(int i=0;i<s.length();i++){
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if(s.charAt(i)=='4' || s.charAt(i)=='7') c++;
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}
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System.out.print((c==4 || c==7)?"YES":"NO");
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reader.close();
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}
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}
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