N,Q=map(int,input().split())
S=list(input())
ans=[]
for _ in range(Q):
    q=list(input().split())
    if q[0]=='1':
        i,c=q[1:]
        i=int(i)-1
        S[i]=c
    else:
        t=q[1]
        if t in ''.join(S):
            ans.append('Yes')
        else:
            ans.append('No')
import sys
sys.stdout.write('\n'.join(map(str,ans))+'\n')