1002 A+B for Polynomials

 1 first_line = input()
 2 second_line = input()
 3 first_line_list = first_line.split( )
 4 second_line_list = second_line.split( )
 5 dict1 = {}
 6 dict2 = {}
 7 for i in range(int(first_line_list[0])):
 8     dict1[first_line_list[i*2 + 1]] = eval(first_line_list[i*2+2]) 
 9 for i in range(int(second_line_list[0])):
10     dict2[second_line_list[i*2 + 1]] = eval(second_line_list[i*2+2])
11 for key in dict2:
12     dict1[key] = dict1.get(key,0) + dict2[key]
13     if dict1[key] == 0:
14         dict1.pop(key)
15 
16 print(len(dict1), end="")
17 dict1=sorted(dict1.items(),key=lambda x:x[0],reverse=True) 
18 for x,y in dict1:
19      print(" {} {:.1f}".format(x,y),end="")