Prg for omit common character from a string in java

class wihoutcommon
 {
     void find(String st)
     {
         int i,j,k,m, flag,f=0;
          char ch,ch1,ch2;
           String wrd="";
          i=st.length();
          for(j=0;j<i;j++)
          {flag=0;
              ch=st.charAt(j);
              for(k=0;k<j;k++)
              {
                  if(ch==st.charAt(k))
                  {
                      flag=1;
                      break;
                    }
                }
                if(flag==0)
                {
                    for(m=j+1;m<i;m++)
                    {f=0;
                        if(ch==st.charAt(m))
                        {
                            f=1;
                            break;
                        }
                    }
                 if(f==0)  
                wrd+=ch;
            }
        }
            System.out.println(wrd);
       
    }
}