1002 A+B for Polynomials (25分)

input1=[eval(i) for i in input().split()]   
input2=[eval(i) for i in input().split()]
d = {}

#查找鍵值的時候順便合併同類項
for i in range(input1[0]):
    a = i*2+1
    d[input1[a]] =  input1[a+1]+d.get(input1[a],0)
for i in range(input2[0]):
    a = i*2+1
    d[input2[a]] =  input2[a+1]+d.get(input2[a],0)

#去掉係數爲0的
for i in list(d.keys()):
    if d[i] == 0:
        del d[i]

#將x[1]之後的按照鍵值排序，默認從小到大
d = sorted(d.items(),key=lambda x:x[0],reverse=True)


print(len(d),end="")
for x,y in d:
    print(" {} {:.1f}".format(x,y),end="")