#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){
    int c = carryLam(x, y);
    if(c == k){
        ans = ans == -1 || y < ans ? y : ans;
    }
}

void solve(){
    ans = -1;
    cin >> x >> k;
    test(1);
    int a[37] = {}, c[37] = {}, pw10[37];
    int _x = x, _k = k;
    for(int i = 0; i < 18; i++){
        a[i] = _x % 10; _x /= 10;
    }

    pw10[0] = 1; for(int i = 1; i <= 36; i++) pw10[i] = pw10[i - 1] * 10;
    int l = 0; while(a[l] == 0) ++l;
    for(int i = 36; i >= l; i--){
        if (a[i + 1] == 9) {
            c[i] = c[i + 1] + 1;
        } else {
            c[i] = 1;
        }
    }
    bool has_upd[37] = {};
    __int128_t res = 0;
    for(int i = l; i <= 36; i++){
        if(_k >= c[i]){
            _k -= c[i];
            for(int j = i + 1; j <= i + c[i]; j++){
                has_upd[j] = true;
            }
            i += c[i] - 1;
        }else if(_k > 0 && c[i] <= k){
            int rm = c[i] - _k;
            for(int i = 0; i <= 36; i++){
                if(has_upd[i] && rm) has_upd[i] = false, rm--;
            }
            for(int j = i + 1; j <= i + c[i]; j++){
                has_upd[j] = true;
            }
            break;
        }
    }
    for(int i = 0; i < 36; i++){
        if(has_upd[i + 1]){
            int s = 10 - a[i];
            if(has_upd[i]) --s;
            res += pw10[i] * s;
        }
    }
    if(res) 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();
    }
}