static int countWords ( String str [ ] , int n ) {
  HashMap < String , Integer > m = new HashMap < > ( ) ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    if ( m . containsKey ( str [ i ] ) ) {
      int get = m . get ( str [ i ] ) ;
      m . put ( str [ i ] , get + 1 ) ;
    }
    else {
      m . put ( str [ i ] , 1 ) ;
    }
  }
  int res = 0 ;
  for ( Map . Entry < String , Integer > it : m . entrySet ( ) ) {
    if ( it . getValue ( ) == 2 ) res ++ ;
  }
  return res ;
}

static int countWords ( String str [ ] , int n ) { HashMap < String , Integer > m = new HashMap < > ( ) ; for ( int i = 0 ; i < n ; i ++ ) { if ( m . containsKey ( str [ i ] ) ) { int get = m . get ( str [ i ] ) ; m . put ( str [ i ] , get + 1 ) ; } else { m . put ( str [ i ] , 1 ) ; } } int res = 0 ; for ( Map . Entry < String , Integer > it : m . entrySet ( ) ) { if ( it . getValue ( ) == 2 ) res ++ ; } return res ; }
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