#include <bits/stdc++.h>

#define int long long
#define all(a) (a).begin(), (a).end()
#define sz(a) (int) (a).size()
#define forn(i, n) for(int i = 0; i < (n); i++)

using namespace std;

int carryLam(__int128_t a, __int128_t b){
    __int128_t c = 0, res = 0;
    while(a > 0 || b > 0){
        int a0 = a % 10, b0 = b % 10; a /= 10; b /= 10;
        if (a0 + b0 + c >= 10) c = 1, res++;
        else c = 0;
    }
    return res;
}

int x, k; 
__int128_t ans = -1;
void test(__int128_t y){
    if(y == 0) return;
    int c = carryLam(x, y);
    if(c == k){
        ans = ans == -1 || y < ans ? y : ans;
    }
}

const int MX = 37;
int d[MX];
__int128_t dp[MX][MX][2];
const __int128_t INF = (((__int128_t) 1) << 120) - 1;
__int128_t pw10[MX];

void chmin(__int128_t& x, __int128_t y){
    x = min(x, y);
}

void solve(){
    ans = -1;
    cin >> x >> k;
    int y = x, l = k;
    for(int i = 0; i < 18; i++) d[i] = y % 10, y /= 10;
    pw10[0] = 1;
    for(int i = 0; i < MX - 1; i++) pw10[i + 1] = pw10[i] * 10;

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

    test(1);
    dp[0][0][0] = 0;

    __int128_t res = INF;
    for(int i = 0; i < MX - 1; i++){
        for(int a = 0; a < 2; a++){
            for(int ok = 0; ok <= k; ok++){
                for(int b = 0; b < 2; b++){
                    if(dp[i][ok][a] == INF) continue;
                    if(ok + b > k) continue;
                    if(d[i] == 0){
                        if(a == 0 && b == 1) continue;
                    }
                    if(d[i] == 9){
                        if(a == 1 && b == 0) continue;
                    }
                    chmin(dp[i + 1][ok + b][b], dp[i][ok][a] + (b ? pw10[i] * (10 - d[i] - a) : 0));
                }
            }
        }
    }

    for(int i = 0; i < MX; i++){
       if(dp[i][k][0] < 0) continue;
        res = min(res, dp[i][k][0]);
    }
    test(res);

    if(ans == -1){
        cout << -1 << '\n';
    }else{
        string r; while(ans > 0) r.push_back('0' + ans % 10), ans /= 10; reverse(all(r));
        cout << r << '\n';
    }
}

int32_t main(){
    cin.tie(0); cout.tie(0)->sync_with_stdio(false);
    int t = 1;
    cin >> t;
    while(t--){
        solve();
    }
}