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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <string.h>
int main(void){
	char s[100];

	scanf("%s",s);

	if(s[0] == '0' && s[1] <= '9' && s[1] != '0'){
		if(s[2] == '0' && s[3] <='9' && s[3] !='0'){
			printf("AMBIGUOUS\n");	
		}else if(s[2] == '1' && s[3] <= '2' && s[3] != '0'){
			printf("AMBIGUOUS\n");
		}else{
			printf("NA\n");
		}
	}else if(s[0] == '0' && s[1] =='0'){
		printf("NA\n");
	}else if(s[2] == '0' && s[3] == '0'){
		printf("NA\n");
	}else if(s[0] == '1' && s[1] <= '2'){
		if(s[2] == '0' && s[3] <='9' && s[3] != '0'){
			printf("AMBIGUOUS\n");	
		}else if(s[2] == '1' && s[3] <= '2'){
			printf("AMBIGUOUS\n");
		}else{
			printf("NA\n");
		}
	}else if(s[0] == '1' && s[1] > '2'){
		if(s[2] == '0' && s[3] <='9' && s[3] != '0'){
			printf("YYMM\n");	
		}else if(s[2] == '1' && s[3] <= '2' && s[3] != '0'){
			printf("YYMM\n");
		}else{
			printf("NA\n");
		}
	}else if(s[0] >1){
		if(s[2] == '0' && s[3] <='9' && s[3] != '0'){
			printf("YYMM\n");	
		}else if(s[2] == '1' && s[3] <= '2' && s[3] != '0'){
			printf("YYMM\n");
		}else{
			printf("NA\n");
		}
	}
	else{
		printf("NA\n");
	}
}