// Author : deetav
// Happy stalking ! ^_^
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
using namespace std;
#define endl "\n"

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);cout.tie(nullptr);cerr.tie(nullptr);
    int64_t t=1;
    cin>>t;
    while(t--)
    {
        int n,x;cin>>n>>x;
        vector <int> lol,v;
        for(int i=0,z;i<n;i++){
            cin>>z;
            lol.push_back(z);v.push_back(z);
        }
        sort(lol.begin(),lol.end());
        if(lol==v){
            cout<<0<<endl;continue;
        }
        bool sorted=false;
       for(int i=0;i<n && !is_sorted(v.begin(),v.end());i++){
           for(int ii=0;ii<n;ii++){
               if(v[ii]>x){
                   swap(x,v[ii]);break;
               }
           }
           if(is_sorted(v.begin(),v.end())){
               sorted=true;
               cout<<i+1<<endl;break;
           }
       }
       if(!sorted){
           cout<<-1<<endl;
       }
    }
    return EXIT_SUCCESS;
}