#include <iostream>
#include <string>
using namespace std;

void work();

int main()
{
	ios::sync_with_stdio(false);
	int t;
	cin >> t;
	while (t--)
		work();
	return 0;
}

void work()
{
	string s, t;
	int k;
	cin >> s >> k;
	for (int i = s.size(); i <= 40; i++)
		t.push_back('0');
	t += s;
	bool bef = 0;
	int cnt = 0;
	string ans;
	for (int i = 0; i < t.size(); i++)
		ans.push_back('0');
	for (int i = t.size() - 1; i >= 0; i--)
	{
		int x = t[i] - '0';
		if (bef)
			x++;
		if (cnt < k)
		{
			int tmp = 10 - x;
			if (tmp >= 10)
				tmp = 0;
			x += tmp;
			ans[i] = '0' + tmp;
		}
		if (x >= 10)
		{
			cnt++;
			bef = true;
		}
		else
			bef = false;
	}
	for (int i = t.size() - 2; i >= 0; i--)
	{
		if (cnt == k)
			break;
		if (ans[i] < '9' && ans[i + 1]>'0')
		{
			ans[i + 1] = '0';
			ans[i]++;
			cnt--;
		}
	}
	if (cnt != k)
	{
		cout << "-1\n";
		return;
	}
	bool flag = false;
	for (char i : ans)
	{
		if (flag || i != '0')
		{
			flag = true;
			cout << i;
		}
	}
	if (!flag)
	{
		cout << '1';
		for (int i = t.size() - 1; i >= 0; i--)
			if (t[i] == '9')
				cout << '0';
	}
	cout << '\n';
	return;
}