import sys
import math
import itertools
import collections
import heapq
import re
import numpy as np

rr = lambda: sys.stdin.readline().rstrip()
rs = lambda: sys.stdin.buffer.readline().split()
ri = lambda: int(sys.stdin.readline())
rm = lambda: map(int, sys.stdin.buffer.readline().split())
rl = lambda: list(map(int, sys.stdin.readline().split()))
inf = float('inf')
mod = 10**9 + 7

a, b = rm()
s = rr()
print(s[:b-1] + s[b-1].lower() + s[b:]) import sys sys import math math import itertools itertools import collections collections import heapq heapq import re re import numpy as np numpy rr = lambda: sys.stdin.readline().rstrip() rr lambda: sys.stdin.readline().rstrip() sys.stdin.readline().rstrip() sys.stdin.readline().rstrip sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline rstrip rs = lambda: sys.stdin.buffer.readline().split() rs lambda: sys.stdin.buffer.readline().split() sys.stdin.buffer.readline().split() sys.stdin.buffer.readline().split sys.stdin.buffer.readline() sys.stdin.buffer.readline sys.stdin.buffer sys.stdin sys stdin buffer readline split ri = lambda: int(sys.stdin.readline()) ri lambda: int(sys.stdin.readline()) int(sys.stdin.readline()) int sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline rm = lambda: map(int, sys.stdin.buffer.readline().split()) rm lambda: map(int, sys.stdin.buffer.readline().split()) map(int, sys.stdin.buffer.readline().split()) map int sys.stdin.buffer.readline().split() sys.stdin.buffer.readline().split sys.stdin.buffer.readline() sys.stdin.buffer.readline sys.stdin.buffer sys.stdin sys stdin buffer readline split rl = lambda: list(map(int, sys.stdin.readline().split())) rl lambda: list(map(int, sys.stdin.readline().split())) list(map(int, sys.stdin.readline().split())) list map(int, sys.stdin.readline().split()) map int sys.stdin.readline().split() sys.stdin.readline().split sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline split inf = float('inf') inf float('inf') float 'inf' mod = 10**9 + 7 mod 10**9 + 7 10**9 10 9 7 a, b = rm() a rm() rm b s = rr() s rr() rr print(s[:b-1] + s[b-1].lower() + s[b:]) print s[:b-1] + s[b-1].lower() + s[b:] s[:b-1] + s[b-1].lower() s[:b-1] s :b-1 b-1 b 1 s[b-1].lower() [b-1].lower [b-1] s b-1 b 1 lower s[b:] s b: b rr = lambda: sys.stdin.readline().rstrip() lambda: sys.stdin.readline().rstrip() rr s = rr() rr() s inf = float('inf') float('inf') inf rs = lambda: sys.stdin.buffer.readline().split() lambda: sys.stdin.buffer.readline().split() rs mod = 10**9 + 7 10**9 + 7 mod rm = lambda: map(int, sys.stdin.buffer.readline().split()) lambda: map(int, sys.stdin.buffer.readline().split()) rm rl = lambda: list(map(int, sys.stdin.readline().split())) lambda: list(map(int, sys.stdin.readline().split())) rl a, b = rm() rm() a ri = lambda: int(sys.stdin.readline()) lambda: int(sys.stdin.readline()) ri b = rm() rm() b
import sys
import math
import itertools
import collections
import heapq
import re
import numpy as np

rr = lambda: sys.stdin.readline().rstrip()
rs = lambda: sys.stdin.buffer.readline().split()
ri = lambda: int(sys.stdin.readline())
rm = lambda: map(int, sys.stdin.buffer.readline().split())
rl = lambda: list(map(int, sys.stdin.readline().split()))
inf = float('inf')
mod = 10**9 + 7

a, b = rm()
s = rr()
print(s[:b-1] + s[b-1].lower() + s[b:])
