#include<bits/stdc++.h>
using namespace std;
int T,n,m,i,j;
string a,b;
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin>>T;
    while(T--){
        cin>>n>>m>>a>>b;
        if(n>m){
            cout<<"No\n";
            continue;
        }
        i=j=0;
        while(i<n&&j<m){
            if(a[i]==b[j]) i++;
            j++;
        }
        cout<<(i==n?"Yes\n":"No\n");
    }
    return 0;
}