Passing cars codility fast

Passing cars codility fast

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        int count=0;
        int pair=0;
        for(int index=0;index<A.length;index++){
            if(A[index]==0){
                count++;
            }else{
                pair+=count;
                if(pair>1000000000){
                 return -1;   
                }
            }
        }
        return pair;
    }
}