class Solution {
public int solution(int[] array) {
int answer = 0;
for (int i=0; i<array.length; i++) {
String word = Integer.toString(array[i]);
for (int j=0; j<word.length(); j++) {
if (word.substring(j, j+1).equals("7")) {
answer += 1;
}
}
}
return answer;
}
}