All numbers with specific difference

#include<bits/stdc++.h>
using namespace std;

int main() {
	int t;
	scanf("%d", &t);
	while (t--) {
		int n, d, i, count = 0;
		cin >> n >> d;
		int l = 0, r = n - 1, mid;
		while (l <= r) {
			mid = l + (r - l) / 2;
			int temp = mid, sum = 0;
			while (temp > 0) {
				sum += temp % 10;
				temp /= 10;
			}
			if ((mid - sum) < d) {
				l = mid + 1;
			}
			else {
				count = n - mid + 1;
				r = mid - 1;
			}
		}
		cout << count << endl;
	}
	return 0;
}