执行下面C++代码可以找出千位与个位的和恰好等于中间两位的四位数，横线处应该填入（ ）

int count = 0;
int a, bc, d, tmp;
for (int i = 1000; i <= 9999; i++) {
    a = (tmp = i) / 1000;
    _________________________
    bc = tmp / 10;
    d = tmp - bc * 10;
    if ( a + d == bc) {
        count++;
    }
}
cout << count;