A_Insert_Digit.cpp

/*

||-------------------------------||
||      Mohiul Islam Miraz       ||
||-------------------------------||

*/

#include <bits/stdc++.h>
#define push                      \
    ios_base::sync_with_stdio(0); \
    cin.tie(NULL);
#define sac sort(v.begin(), v.end())
#define sdc sort(v.begin(), v.end(), greater<int>())
#define f1 bool flag = true
#define f0 bool flag = false
#define c0 int count = 0
#define c1 int count = 1
#define s0 long long sum = 0
#define a0 long long ans = 0
#define ll long long
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#define minus cout << -1 << endl
#define cnt cout << count << endl
#define sm cout << sum << endl
using namespace std;

int main()
{
    int t;
    cin >> t;
    while (t--)
    {
        int n, d;
        string s;
        cin >> n >> d >> s;

        int pos = -1;

        for (int i = 0; i < n; i++)
        {
            if (d > (s[i] - '0'))
            {
                pos = i;
                break;
            }
        }
        if (pos == -1)
        {
            cout << s << d << endl;
        }
        else
        {
            s.insert(pos, to_string(d));
            cout << s << endl;
        }
    }
}