int count = 0;
    if(B.size() <= 1) return "NO";
    else {
        for(int i = 0; i< B.size(); i++){
            if(B[i]%2 == 0) continue;
            if (i + 1 < B.size()) {
                B[i]++;
                B[i + 1]++;
                count += 2;
            }
        }
    }
    
    return B[B.size()-1]%2 == 0? to_string(count) : "NO";