#include<bits/stdc++.h>

using namespace std;

#define int long long

void solve(){
	string s;
	cin >> s;
	int n = s.size();
	int k;
	cin >> k;
	if (k == 0){
		int x = 1;
		for (int i = 1;i <= n;i ++){
			if (s[n - i] == '9') x *= 10;
			else{
				cout << x << "\n";
				return;
			}
		}
		cout << "-1\n";
		return;
	}
	if (k > n){
		for (int i = 0;i < k - n;i ++)
			cout << '9';
		k = n;
	}
	int dp[n + 1][k + 1][2] = {};
	memset(dp,0x3f,sizeof dp);
	dp[0][0][0] = 0;
	if (s[0] != '0') dp[0][1][1] = ('9' - s[n - 1]) + 1;
	int q = 1;
	for (int i = 1;i < n;i ++){
		q = q * 10;
		dp[i][0][0] = 0;
		for (int  j = 1;j <= k;j ++){
			dp[i][j][0] = dp[i - 1][j][0];
			if (s[i] != '9') dp[i][j][0] = min(dp[i][j][0] , dp[i - 1][j][1]);
			dp[i][j][1] = dp[i - 1][j - 1][1] + q * ('9' - s[n - i - 1]);
			if (s[i] != '0') dp[i][j][1] = min(dp[i][j][1],dp[i - 1][j - 1][0] + q * ('9' - s[n - i - 1] + 1));
		}
	}
	cout << min(dp[n - 1][k][0],dp[n - 1][k][1]) << "\n";
}

signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
	int t;
	cin >> t;
	while(t --){
		solve();
	}
}