def intMap(): return map(int,input().split())

n,k = intMap()
s = input()

ans = s[:k-1] + s[k-1].lower() + s[k:]
print(ans) def intMap(): return map(int,input().split()) intMap n,k = intMap() n intMap() intMap k s = input() s input() input ans = s[:k-1] + s[k-1].lower() + s[k:] ans s[:k-1] + s[k-1].lower() + s[k:] s[:k-1] + s[k-1].lower() s[:k-1] s :k-1 k-1 k 1 s[k-1].lower() [k-1].lower [k-1] s k-1 k 1 lower s[k:] s k: k print(ans) print ans s = input() input() s n,k = intMap() intMap() n def intMap(): return map(int,input().split()) def intMap(): return map(int,input().split()) intMap k = intMap() intMap() k ans = s[:k-1] + s[k-1].lower() + s[k:] s[:k-1] + s[k-1].lower() + s[k:] ans
def intMap(): return map(int,input().split())

n,k = intMap()
s = input()

ans = s[:k-1] + s[k-1].lower() + s[k:]
print(ans)
