# include<iostream>

# include<cstdio>

# include<queue>

# include<vector>

# include<list>

# include<map>

# include<set>

# include<cstdlib>

# include<string>

# include<cstring>

# include<algorithm>

using namespace std;

# define LL long long

const int N=1000;

const int INF=1<<30;

const LL oo=1e15;

const double eps=1e-20;

int n,m;

int sum[N*100+5];

int main()

{

	int T;

	scanf("%d",&T);

	while(T--)

	{

		scanf("%d%d",&n,&m);

		memset(sum,0,sizeof(sum));

		int a,k=0;

		for(int i=0;i<n;++i){

			scanf("%d",&a);

			if(a) sum[a]=1;

			else ++k;

		}

		for(int i=1;i<=m;++i)

			sum[i]+=sum[i-1];

		int ans=0;

		for(int i=1;i<=m;++i){

			int l=i,r=m;

			while(l<=r){

				int x=(l+r)>>1;

				if(sum[x]-sum[i-1]+k>=x-i+1){

					ans=max(ans,x-i+1);

					l=x+1;

				}else{

					r=x-1;

				}

			}

		}

		printf("%d\n",ans);

	}

	return 0;

}