def mutate_string(string, position, character): s_new = string[:position] + character + string[position+1:] return s_new

if name == 'main': s = input() i, c = input().split() s_new = mutate_string(s, int(i), c) print(s_new)

def mutate_string(string, position, character): a = list(string) a[position] = character k = "".join(a) return k

def mutate_string(string, position, character):

q = list(string)
q[position] = f'{character}'
length = len(q)
ss = ""
x=0
def concatinate():
    nonlocal q
    nonlocal x
    nonlocal ss 
    if x < length :
        ss+= str(q[x]) 
        x+=1 
        return concatinate()
concatinate()    
print(ss)

mutate_string("eerwewewe232xz",8,"%@#!")

def mutate_string(string, position, character): l= list(string) l[position] = character return "".join(l)

if name == 'main': s = input() i, c = input().split() s_new = mutate_string(s, int(i), c) print(s_new)