It's Your Choice.

t=int(input())
for T in range(0,t):
    n,m = map(int,input().split())
    a=input()
    b=input()
    flag=0
    for i in range(0,n-m+1):
        if a[i]==b[0]:
            flag=1
    for i in range(n-m+1,n):
        if a[i]!=b[i-(n-m)]:
            flag=0
    if flag==1:
        print("YES")
    else:
        print("NO")