#include <bits/stdc++.h>

#define int ll
using ll = unsigned long long;

// #define MING_LE

const int mod = 998244353;
const __int128_t inf = 1e36;

using namespace std;

int a[40];
int b[40];
__int128_t dp[40][40][2];
__int128_t ten[40];

void out(__int128_t x);
void solve();

signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int __ = 1;
    cin >> __;

    ten[0] = 1;
    for (int i = 1; i <= 36; i++)
    {
        ten[i] = ten[i - 1] * 10;
    }

    while (__--)
        solve();

    return 0;
}

void solve()
{
    int now;
    int n, m;
    n = 0;
    cin >> now >> m;

    for (int i = 0; i <= 36; i++)
    {
        a[i] = 0;
        b[i] = 0;
    }

    while (now)
    {
        b[n] = now % 10;
        now /= 10;
        n++;
    }

    for (int i = 0; i <= 36; i++)
    {
        a[i] = 1;
        for (int j = i + 1; j <= 36; j++)
        {
            if (b[j] != 9)
                break;
            a[i]++;
        }
    }

    for (int i = 0; i <= 36; i++)
    {
        for (int j = 0; j <= 36; j++)
        {
            for (int k = 0; k <= 1; k++)
                dp[i][j][k] = inf;
        }
    }

    dp[0][0][0] = 0;
    for (int i = 0; i <= 36; i++)
    {
        for (int j = 0; j <= 36; j++)
        {
            for (int k = 0; k <= 1; k++)
            {
                if (k == 0 && i > 0)
                    dp[i][j][k] = min(dp[i][j][k], min(dp[i - 1][j][0], dp[i - 1][j][1]));
                __int128_t buffer = 0;
                int flag = k;
                if (b[i] == 0 && flag == 0)
                    continue;
                buffer += (10 - flag - b[i]) * ten[i];
                // for (int p = i; p < i + a[i] + (a[i] == 0 ? flag : 0); p++)
                // {
                //     buffer += (10 - flag - b[p]) * ten[p];
                //     flag = 1;
                // }

                dp[i + a[i]][j + a[i]][1] = min(dp[i][j][k] + buffer, dp[i + a[i]][j + a[i]][1]);
            }
        }
    }

    __int128_t ans = inf;
    for (int i = 0; i <= 36; i++)
        for (int k = 0; k <= 1; k++)
        {
            ans = min(ans, dp[i][m][k]);
#ifdef MING_LE
            cout << i << " " << k << " ";
            out(dp[i][m][k]);
            cout << '\n';
#endif
        }

    if (ans < inf)
    {
        out(ans);
        cout << '\n';
    }
    else
        cout << "-1\n";
}

void out(__int128_t x)
{
    stack<int> sck;
    while (x > 0)
    {
        sck.push(x % 10);
        x /= 10;
    }
    if (sck.empty())
    {
        cout << "0";
        return;
    }
    while (!sck.empty())
    {
        cout << sck.top();
        sck.pop();
    }
}

/*
4
12345678 0
12345678 5
12345678 18
990099 5
*/

/*
1
99999999999999999 1
*/

/*
1
1000000000000000000 18
*/

/*
1
990099990099 5
*/