Problem:
Score : 100 points

Problem Statement

You are given four digits N_1, N_2, N_3 and N_4. Determine if these can be arranged into the sequence of digits "1974".

Constraints

0 \leq N_1, N_2, N_3, N_4 \leq 9

N_1, N_2, N_3 and N_4 are integers.

Input

Input is given from Standard Input in the following format:

N_1 N_2 N_3 N_4

Output

If N_1, N_2, N_3 and N_4 can be arranged into the sequence of digits "1974", print YES; if they cannot, print NO.

Sample Input 1

1 7 9 4

Sample Output 1

YES

We can get 1974 by swapping N_2 and N_3.

Sample Input 2

1 9 7 4

Sample Output 2

YES

We already have 1974 before doing anything.

Sample Input 3

1 2 9 1

Sample Output 3

NO

Sample Input 4

4 9 0 8

Sample Output 4

NO

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
using namespace std;

int main(){
    int s[4];
    cin >> s[0] >> s[1] >> s[2] >> s[3];

    int cnt1=0;
    int cnt2=0;
    int cnt3=0; 
    int cnt4=0;

    for(int i = 0; i < 4; i++) {
        if(s[i] == 1) {
            cnt1++;
        } else if (s[i] == 9) {
            cnt2++;
        } else if (s[i] == 7) {
            cnt3++;
        } else if (s[i] == 4) {
            cnt4++;
        }
    }

    if(cnt1 == 1 && cnt2 == 1 && cnt3 == 1 && cnt4 == 1) {
        cout <<  "YES" << endl;
    } else {
        cout << "NO" << endl;
    }

}