// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
// write your code in Java SE 8
int answer = 0;
int zeroCount = 0;
for(int i=0; i<A.length; i++) {
if(A[i] == 0) {
zeroCount++;
} else {
answer += zeroCount;
if(answer > 1_000_000_000) {
return -1;
}
}
}
return answer;
}
}