import java.util.*;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int K = sc.nextInt();
        // 文字列の入力
        String S = sc.next(); 
      //変換
      char[] A = S.toCharArray();
      
      int M = K-1;
     int sabun ='A'-'a';

      int z = (int)A[M]-sabun;
      
      A[M] = (char)z;

   
        // 出力
        System.out.println(A);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int K = sc.nextInt();
        // 文字列の入力
        String S = sc.next(); 
      //変換
      char[] A = S.toCharArray();
      
      int M = K-1;
     int sabun ='A'-'a';

      int z = (int)A[M]-sabun;
      
      A[M] = (char)z;

   
        // 出力
        System.out.println(A);
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int K = sc.nextInt();
        // 文字列の入力
        String S = sc.next(); 
      //変換
      char[] A = S.toCharArray();
      
      int M = K-1;
     int sabun ='A'-'a';

      int z = (int)A[M]-sabun;
      
      A[M] = (char)z;

   
        // 出力
        System.out.println(A);
    } main {
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int K = sc.nextInt();
        // 文字列の入力
        String S = sc.next(); 
      //変換
      char[] A = S.toCharArray();
      
      int M = K-1;
     int sabun ='A'-'a';

      int z = (int)A[M]-sabun;
      
      A[M] = (char)z;

   
        // 出力
        System.out.println(A);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int K = sc.nextInt(); K sc.nextInt() sc.nextInt sc String S = sc.next(); S sc.next() sc.next sc char[] A = S.toCharArray(); A S.toCharArray() S.toCharArray S int M = K-1; M K-1 K 1 int sabun ='A'-'a'; sabun 'A'-'a' 'A' 'a' int z = (int)A[M]-sabun; z (int)A[M]-sabun (int)A[M] A M sabun A[M] = (char)z A[M] A M (char)z System.out.println(A) System.out.println System.out System System.out A String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int K = sc.nextInt();
        // 文字列の入力
        String S = sc.next(); 
      //変換
      char[] A = S.toCharArray();
      
      int M = K-1;
     int sabun ='A'-'a';

      int z = (int)A[M]-sabun;
      
      A[M] = (char)z;

   
        // 出力
        System.out.println(A);
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int K = sc.nextInt();
        // 文字列の入力
        String S = sc.next(); 
      //変換
      char[] A = S.toCharArray();
      
      int M = K-1;
     int sabun ='A'-'a';

      int z = (int)A[M]-sabun;
      
      A[M] = (char)z;

   
        // 出力
        System.out.println(A);
    }
} Main
import java.util.*;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int N = sc.nextInt();
        int K = sc.nextInt();
        // 文字列の入力
        String S = sc.next(); 
      //変換
      char[] A = S.toCharArray();
      
      int M = K-1;
     int sabun ='A'-'a';

      int z = (int)A[M]-sabun;
      
      A[M] = (char)z;

   
        // 出力
        System.out.println(A);
    }
}