a,b=map(int,input().split())
s=list(input())
wd=''
cnt=1
for i in s:
    if cnt==b:
        cnt+=1
        wd+=(i.lower())
    else:
        cnt+=1
        wd+=(i)
print(wd) a,b=map(int,input().split()) a map(int,input().split()) map int input().split() ().split () input split b s=list(input()) s list(input()) list input() input wd='' wd '' cnt=1 cnt 1 for i in s:
    if cnt==b:
        cnt+=1
        wd+=(i.lower())
    else:
        cnt+=1
        wd+=(i) i s if cnt==b:
        cnt+=1
        wd+=(i.lower())
    else:
        cnt+=1
        wd+=(i) cnt==b cnt b cnt+=1 cnt 1 wd+=(i.lower()) wd i.lower() i.lower i lower cnt+=1 cnt 1 wd+=(i) wd i print(wd) print wd cnt+=1 1 cnt cnt+=1 1 cnt wd+=(i) i wd a,b=map(int,input().split()) map(int,input().split()) a b=map(int,input().split()) map(int,input().split()) b wd+=(i.lower()) i.lower() wd wd='' '' wd s=list(input()) list(input()) s cnt=1 1 cnt
a,b=map(int,input().split())
s=list(input())
wd=''
cnt=1
for i in s:
    if cnt==b:
        cnt+=1
        wd+=(i.lower())
    else:
        cnt+=1
        wd+=(i)
print(wd)