def find_the_diff(s, t):
 t_dict = {}
 s_dict = {}
 for i in s:
  s_dict[i] = (s_dict.get(i, 0) + 1)
 for i in t:
  t_dict[i] = (t_dict.get(i, 0) + 1)
 for i in t_dict.keys():
  if (t_dict[i] > s_dict.get(i, 0)):
   return i

def find_the_diff ( s , t ) : t_dict = { } s_dict = { } for i in s : s_dict [ i ] = ( s_dict . get ( i , 0 ) + 1 ) for i in t : t_dict [ i ] = ( t_dict . get ( i , 0 ) + 1 ) for i in t_dict . keys ( ) : if ( t_dict [ i ] > s_dict . get ( i , 0 ) ) : return i
s: string .