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;
#define ll            long long
#define nl            "\n"
#define PB            push_back
#define fi            first
#define se            second
#define _SAD()        ios::sync_with_stdio(0),cin.tie(0), cout.tie(0);
#define rep(i,n)      for(int i=0;i<n;i++)
#define repn(i,n)     for(int i=1;i<=n;i++)
#define rrep(i,n)      for(int i=n-1;i>=0;i--)
#define SZ(s)         s.size()
#define SRT(x,y)      sort(x,x+y)
#define REV(a,b)      reverse(a,a+b)
#define VSRT(x)       sort(x.begin(),x.end())
#define VREV(x)       reverse(x.begin(),x.end())
/*-----------------------------------------------------------------------------------------------*/
const int N = 1e5+10;
int n,k;
string s;
int main()
{
    _SAD()
    cin>>n>>k>>s;
    s[k-1]+=32;
    cout<<s<<nl;
    return 0;
}