Problem:
Score : 100 points

Problem Statement

You are given a string S of length N consisting of A, B and C, and an integer K which is between 1 and N (inclusive).
Print the string S after lowercasing the K-th character in it.

Constraints

1 ≤ N ≤ 50

1 ≤ K ≤ N

S is a string of length N consisting of A, B and C.

Input

Input is given from Standard Input in the following format:

N K
S

Output

Print the string S after lowercasing the K-th character in it.

Sample Input 1

3 1
ABC

Sample Output 1

aBC

Sample Input 2

4 3
CABA

Sample Output 2

CAbA

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef pair<ll, ll> Pl;

const int INT_INF = 2147483646;
const ll LL_INF = 9223372036854775807;
const double PI=3.1415926535897932;

bool SecondCompare(const pair<int,int> &a,const pair<int,int> &b)
{
       return a.second<b.second;
}
 
bool SecondCompareDes(const pair<int,int> &a,const pair<int,int> &b)
{
       return a.second>b.second;
}

ll minll(ll a, ll b){
    if(a >= b)  return b;
    else    return a;
}

ll maxll(ll a, ll b){
    if(a >= b)  return a;
    else    return b;
}

ll n,k;
string s;

int main(){
    cin >> n >> k;
    cin >> s;
    if(s[k-1] == 'A') s[k-1] = 'a';
    if(s[k-1] == 'B') s[k-1] = 'b';
    if(s[k-1] == 'C') s[k-1] = 'c';
    cout << s << endl;
}