import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        k--;
    //    int f[] = new int[k];
   String s = sc.next();
         
       char c[] = s.toCharArray();
      s = s.toLowerCase();
     char d []  = s.toCharArray();
       
        for(int i=0 ; i<n ; i++){
       if(i==k)
       {
           c[i] = d[k];
           break ;
       }
        
    }   for(int i = 0 ; i <c.length ; i++)
        System.out.print(c[i]);
} 
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        k--;
    //    int f[] = new int[k];
   String s = sc.next();
         
       char c[] = s.toCharArray();
      s = s.toLowerCase();
     char d []  = s.toCharArray();
       
        for(int i=0 ; i<n ; i++){
       if(i==k)
       {
           c[i] = d[k];
           break ;
       }
        
    }   for(int i = 0 ; i <c.length ; i++)
        System.out.print(c[i]);
} 
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        k--;
    //    int f[] = new int[k];
   String s = sc.next();
         
       char c[] = s.toCharArray();
      s = s.toLowerCase();
     char d []  = s.toCharArray();
       
        for(int i=0 ; i<n ; i++){
       if(i==k)
       {
           c[i] = d[k];
           break ;
       }
        
    }   for(int i = 0 ; i <c.length ; i++)
        System.out.print(c[i]);
} main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        k--;
    //    int f[] = new int[k];
   String s = sc.next();
         
       char c[] = s.toCharArray();
      s = s.toLowerCase();
     char d []  = s.toCharArray();
       
        for(int i=0 ; i<n ; i++){
       if(i==k)
       {
           c[i] = d[k];
           break ;
       }
        
    }   for(int i = 0 ; i <c.length ; i++)
        System.out.print(c[i]);
} 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 k-- k String s = sc.next(); s sc.next() sc.next sc char c[] = s.toCharArray(); c s.toCharArray() s.toCharArray s s = s.toLowerCase() s s.toLowerCase() s.toLowerCase s char d []  = s.toCharArray(); d s.toCharArray() s.toCharArray s for(int i=0 ; i<n ; i++){
       if(i==k)
       {
           c[i] = d[k];
           break ;
       }
        
    } int i=0 ; int i=0 ; i 0 i<n i n i++ i++ i {
       if(i==k)
       {
           c[i] = d[k];
           break ;
       }
        
    } {
       if(i==k)
       {
           c[i] = d[k];
           break ;
       }
        
    } if(i==k)
       {
           c[i] = d[k];
           break ;
       } i==k i k {
           c[i] = d[k];
           break ;
       } c[i] = d[k] c[i] c i d[k] d k break ; for(int i = 0 ; i <c.length ; i++)
        System.out.print(c[i]); int i = 0 ; int i = 0 ; i 0 i <c.length i c.length c c.length i++ i++ i System.out.print(c[i]); System.out.print(c[i]) System.out.print System.out System System.out c[i] c i String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        k--;
    //    int f[] = new int[k];
   String s = sc.next();
         
       char c[] = s.toCharArray();
      s = s.toLowerCase();
     char d []  = s.toCharArray();
       
        for(int i=0 ; i<n ; i++){
       if(i==k)
       {
           c[i] = d[k];
           break ;
       }
        
    }   for(int i = 0 ; i <c.length ; i++)
        System.out.print(c[i]);
} 
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        k--;
    //    int f[] = new int[k];
   String s = sc.next();
         
       char c[] = s.toCharArray();
      s = s.toLowerCase();
     char d []  = s.toCharArray();
       
        for(int i=0 ; i<n ; i++){
       if(i==k)
       {
           c[i] = d[k];
           break ;
       }
        
    }   for(int i = 0 ; i <c.length ; i++)
        System.out.print(c[i]);
} 
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        k--;
    //    int f[] = new int[k];
   String s = sc.next();
         
       char c[] = s.toCharArray();
      s = s.toLowerCase();
     char d []  = s.toCharArray();
       
        for(int i=0 ; i<n ; i++){
       if(i==k)
       {
           c[i] = d[k];
           break ;
       }
        
    }   for(int i = 0 ; i <c.length ; i++)
        System.out.print(c[i]);
} 
}
