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: Wrong Answer)

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
int main()
{
	string s;
	cin>>s;
	int a[4];
	a[0]=s[0]-'0';a[1]=s[1]-'0';
	a[2]=s[2]-'0';a[3]=s[3]-'0';
	int m1=a[0]*10+a[1];
	int m2=a[2]*10+a[3];
	if(!m2||!m1){
		if(!m1&&m2!=0){
			if(m2<=12){
				cout<<"YYMM";
			}
			else{
				cout<<"NA";
			}
		}
		//cout<<"NA";
		if(!m2&&m1!=0){
			if(m1<=12){
				cout<<"MMYY";
			}
			else{
				cout<<"NA";
			}
		}
		if(m1==0&&m2==0){
			cout<<"NA";
		}
	}
	else{
		if(m2<=12){
			if(m1<=12){
				cout<<"AMBIGUOUS";
			}
			else{
				cout<<"YYMM";
			}
		}
		else{
			if(m1<=12){
				cout<<"MMYY";
			}
			else{
				cout<<"NA";
			}
		}
	}
	return 0;
}