import java.io.*;
import java.util.*;

class  CountCharacters {
  public static void main(String[] args) throws Exception{
  BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
  System.out.print("Please enter string ");
  System.out.println();
  String str=br.readLine();
  String st=str.replaceAll(" ", "");

  char[]third =st.toCharArray();
  for(int counter =0;counter<third.length;counter++){
  char ch= third[counter];
  int count=0;
  for ( int i=0; i<third.length; i++){
  if (ch==third[i])
  count++;
}
boolean flag=false;
for(int j=counter-1;j>=0;j--){
if(ch==third[j])
flag=true;
}
if(!flag){
System.out.println("Character :"+ch+" occurs "+count+" times ");
}
}
}
}

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Java Count Characters