#include <iostream>
#include <algorithm>
#include <cstdio>
#include <array>
#include <cstring>
using namespace std;

const int MAXN = 3e6 + 5, N = 3e6 + 5;

bool _stmer;

using ll=long long int;
using namespace std;

struct Bigint {
    string a;
    int sign;

    Bigint(){}
    void operator = (string b) {
        a= (b[0]=='-' ? b.substr(1) : b);
        reverse(a.begin(), a.end());
        (*this).Remove0(b[0]=='-' ? -1 : 1);
    }
    Bigint(string x) {(*this)=x;}
    Bigint(ll x) {(*this)=to_string(x);}
    void operator = (ll x){*this=to_string(x);}

    char operator[](int i){return a[i];}
    int size() {return a.size();}
    Bigint inverseSign() {sign*=-1; return (*this);}

    Bigint Remove0(int newSign) {
        sign = newSign;
        for(int i=a.size()-1; i>0 && a[i]=='0'; i--) a.pop_back();
        if(a.size()==1 && a[0]=='0') sign=1;
        return (*this);
    }

    bool operator == (Bigint x) {return sign==x.sign && a==x.a;}
    bool operator == (string x) {return *this==Bigint(x);}
    bool operator == (ll x)     {return *this==Bigint(x);}
    bool operator != (Bigint x) {return !(*this==x);}
    bool operator != (string x) {return !(*this==x);}
    bool operator != (ll x)     {return !(*this==x);}

    bool operator < (Bigint b) {
        if (sign!=b.sign) return sign<b.sign;
        if(a.size()!=b.size()) return a.size()*sign<b.size()*sign;
        for(int i=a.size()-1; i>=0; i--)
            if(a[i] != b[i]) return a[i]<b[i];
        return false;
    }
    bool operator <  (string x) {return *this<Bigint(x);}
    bool operator <  (ll x)     {return *this<Bigint(x);}
    bool operator <= (Bigint b) {return *this==b || *this<b;}
    bool operator <= (string b) {return *this==b || *this<b;}
    bool operator <= (ll b)     {return *this==b || *this<b;}
    bool operator >  (Bigint b) {return !(*this==b || *this<b);}
    bool operator >  (string x) {return !(*this==x || *this<x);}
    bool operator >  (ll b)     {return !(*this==b || *this<b);}
    bool operator >= (Bigint b) {return *this==b || *this>b;}
    bool operator >= (string b) {return *this==b || *this>b;}
    bool operator >= (ll b)     {return *this==b || *this>b;}

    Bigint operator + (Bigint b) {
        if(sign != b.sign) return (*this)-b.inverseSign();
        Bigint sum;
        for(int i=0, carry=0; i<a.size() || i<b.size() || carry; i++){
            if (i<a.size()) carry+=a[i]-'0';
            if (i<b.size()) carry+=b[i]-'0';
            sum.a += (carry % 10 + 48);
            carry /= 10;
        }
        return sum.Remove0(sign);
    }
    Bigint operator +  (string x) {return *this+Bigint(x);}
    Bigint operator +  (ll x)     {return *this+Bigint(x);}
    Bigint operator ++ (int) {*this+=1; return *this-1;}
    Bigint operator ++ ()    {*this+=1; return *this;}
      void operator += (Bigint x) {*this = *this+x;}
      void operator += (string x) {*this = *this+x;}
      void operator += (ll x)     {*this = *this+x;}


    Bigint operator - ( Bigint b ) {
        if(sign != b.sign) return (*this)+b.inverseSign();
        if(*this < b) return (b - *this).inverseSign();
        Bigint sub;
        for(int i=0,borrow=0; i<a.size(); i++) {
            borrow = a[i]-borrow-(i<b.size() ? b.a[i] : '0');
            sub.a += borrow>=0 ? borrow+'0' : borrow + 58;
            borrow = borrow>=0 ? 0:1;
        }
        return sub.Remove0(sign);
    }
    Bigint operator - (string x) {return *this-Bigint(x);}
    Bigint operator - (ll x)     {return *this-Bigint(x);}
    Bigint operator -- (int) {*this-=1; return *this+1;}
    Bigint operator -- ()    {*this-=1; return *this;}
      void operator -= (Bigint x) {*this = *this-x;}
      void operator -= (string x) {*this = *this-x;}
      void operator -= (ll x)     {*this = *this-x;}

    Bigint operator * (Bigint b) {
        Bigint mult("0");
        for(int i=0, k=a[i]; i<a.size(); i++, k=a[i]) {
            while(k-- -'0') mult=mult+b;
            b.a.insert(b.a.begin(),'0');
        }
        return mult.Remove0(sign * b.sign);
    }
    Bigint operator * (string x) {return *this*Bigint(x);}
    Bigint operator * (ll x)     {return *this*Bigint(x);}
      void operator *= (Bigint x) {*this = *this*x;}
      void operator *= (string x) {*this = *this*x;}
      void operator *= (ll x)     {*this = *this*x;}

    Bigint operator / (Bigint b) {
        if(b.size()==1 && b[0]=='0') b.a[0]/=(b[0]-'0');
        Bigint c("0"), d;
        for(int j=0; j<a.size(); j++) d.a += "0";
        int dSign = sign*b.sign; b.sign=1;
        for(int i=a.size()-1; i>=0; i--) {
            c.a.insert(c.a.begin(),'0');
            c=c+a.substr(i,1);
            while(!(c<b)) c=c-b, d.a[i]++;
        }
        return d.Remove0(dSign);
    }
    Bigint operator / (string x) {return *this/Bigint(x);}
    Bigint operator / (ll x)     {return *this/Bigint(x);}
      void operator /= (Bigint x) {*this = *this/x;}
      void operator /= (string x) {*this = *this/x;}
      void operator /= (ll x)     {*this = *this/x;}

    Bigint operator % (Bigint b) {
        if( b.size()==1 && b[0]=='0') b.a[0]/=(b[0]-'0') ;
        Bigint c("0");
        int cSign = sign*b.sign; b.sign=1;
        for( int i=a.size()-1; i>=0; i-- ) {
            c.a.insert( c.a.begin(),'0');
            c = c+a.substr(i,1);
            while(!(c<b)) c=c-b;
        }
        return c.Remove0(cSign);
    }
    Bigint operator % (string x) {return *this%Bigint(x);}
    Bigint operator % (ll x)     {return *this%Bigint(x);}
      void operator %= (Bigint x) {*this = *this%x;}
      void operator %= (string x) {*this = *this%x;}
      void operator %= (ll x)     {*this = *this%x;}

    void print() {
        if(sign==-1) putchar('-');
        for(int i=a.size()-1; i>=0; i--) putchar(a[i]);
    }
    friend istream& operator >>(istream &in,Bigint &x){
        string s; in>>s; x=s; return in;
    }
    friend ostream& operator <<(ostream &out,Bigint &x){
        if(x.sign==-1) putchar('-');
        for(int i=x.size()-1; i>=0; i--)
            putchar(x[i]);
        return out;
    }

    friend Bigint pow(Bigint base, Bigint pw){
        Bigint ans=1;
        while(pw!=0){
            if(pw%2 !=0) ans*=base;
            base*=base, pw/=2;
        }
        return ans;
    }
    friend Bigint pow(Bigint a, Bigint b,Bigint mod) {
        if (b==0) return Bigint(1);
        Bigint tmp=pow(a,b/2,mod);
        if ((b%2)==0) return (tmp*tmp)%mod;
        else return (((tmp*tmp)%mod)*a)%mod;
    }
    friend Bigint sqrt(Bigint x) {
        Bigint ans=x,tmp=(x+1)/2;
        while (tmp<ans) ans=tmp, tmp=(tmp+x/tmp)/2;
        return ans;
    }
    friend Bigint gcd(Bigint a,Bigint b){
        return a%b==0 ? b : gcd(b, a%b);
    }
    friend Bigint lcm(Bigint a,Bigint b){
        return a/gcd(a,b);
    }
};

#define bign Bigint

void solve() {
    bign n, m;
    cin >> n >> m;
    bign ans = n + m - (n % m);
    bign res1 = n + 1;

    bool flg1 = 0;
    for (int i = 0; i + m.size() < res1.size(); i++) {
        bool flg = 0;
        for (int j = m.size() - 1; ~j; j--)
            if (res1[i + j] != m[j]) { flg = 1; break; }
        if (flg) continue;
        flg1 = 1; break;
    }
    if (flg1) { return (void)(cout << res1 << endl); }

    bign res2; int pos2 = -1;
    for (int i = 0; i + m.size() < n.size(); i++) {
        bool flg = 0;
        for (int j = m.size() - 1; ~j; j--) {
            if (res1[i + j] == m[j]) continue;
            if (res1[i + j] > m[j]) { flg = 1; break; }
            if (res1[i + j] < m[j]) { flg = 0; break; }
        }
        if (flg) continue;
        pos2 = i;
    }
    if (~pos2) {
        bign tp;
        for (int i = pos2 + m.size(); i < n.size(); i++)
            tp.a.push_back(n[i]);
        tp = tp;
        for (int i = 0; i < pos2; i++)
            res2.a.push_back('0');
        int pos3 = pos2 + m.size();
        for (int i = pos2; i < pos3; i++)
            res2.a.push_back(m[i - pos2]);
        for (int i = pos3; i < pos3 + tp.size(); i++)
            res2.a.push_back(tp[i - pos3]);
    }

    bign res3;
    for (int i = 0; i < m.size(); i++)
        res3.a.push_back(m[i]);
    bign tp;
    for (int i = m.size(); i < n.size(); i++)
        tp.a.push_back(n[i]);
    tp = tp + 1;
    for (int i = m.size(); i < m.size() + tp.size(); i++)
        res3.a.push_back(tp[i - m.size()]);
    if (res2.size() && res2 < res3)
        res3 = res2;
    if (res3 < ans) cout << res3 << endl;
    else cout << ans << endl;
}

bool _edmer;
int main() {
    cerr << (&_stmer - &_edmer) / 1024.0 / 1024.0 << "MB\n";
    /* freopen("in.txt", "r", stdin); */
    int T; cin >> T;
    while (T--) solve();
    return 0;
}