TypeError: 'str' object is not callable python [duplicate]

i am new to python i am geeting the error TypeError: 'str' object is not callable

when input is

3
111+23
1638-1350
1992+133

then porgram run successfully but when the input string contain '*' means my else condition then it throe TypeError

for example if input is

3
111*23
1638-1350
110+456

then got the error TypeError: 'str' object is not callable

here is my code link to ideone code-> http://ideone.com/bDuXpW

def MAX(a,b,c):
    if(a>b and a>c):
        return a
    elif(b>a and b>c):
        return b
    else:
        return c

t=input()
for x in range(0,t):
    myinput=raw_input()
    if(myinput.find('+')!=-1):
        num1,num2=myinput.split('+')
        result=int(num1)+int(num2)
        result_str=str(result)
        num2='+'+num2
        len1=len(num1)
        len2=len(num2)
        len3=len(result_str)
        max=MAX(len1,len2,len3)
        line='-'*max
        num1=' '*(max-len1)+num1
        num2=' '*(max-len2)+num2
        result_str=' '*(max-len3)+result_str
        print num1
        print num2
        print line
        print result_str
        print '\n'
    elif(myinput.find('-')!=-1):
        num1,num2=myinput.split('-')
        result=int(num1)-int(num2)
        result_str=str(result)
        num2='-'+num2
        len1=len(num1)
        len2=len(num2)
        len3=len(result_str)
        max=MAX(len1,len2,len3)
        line='-'*max
        num1=' '*(max-len1)+num1
        num2=' '*(max-len2)+num2
        result_str=' '*(max-len3)+result_str
        print num1
        print num2
        print line
        print result_str
        print '\n'
    else:
        num1,num2=myinput.split('*')
        result=int(num1)*int(num2)  
        result_str=str(result)
        num1_int=int(num1)
        ascii_num2=[]
        for y in num2:
            ascii_num2.append(ord(y)-48)
        mul_list=[]
        k=0
        num2='*'+num2
        len1=len(num1)
        len2=len(num2)
        len3=len(result_str)
        max=MAX(len1,len2,0)
        line='-'*max
        for dig2 in  reversed(ascii_num2):
            new=dig2*(num1_int)
            new_str=str(new)+' '*k
            mul_list.append(new_str)
            k+=1        
        count=len(mul_list)
        max=MAX(len1,len2,len3)
        num1=' '*(max-len1)+num1
        num2=' '*(max-len2)+num2
        line=' '*(max-len(line))+line
        another_line='-'*max
        for i in range(0,count):
            str=mul_list[i]
            str=' '*(max-len(str))+str
            mul_list[i]=str
        print num1
        print num2
        print line
        for i in range(0,count):
            print mul_list[i]
        print another_line
        print result_str
        print '\n'
        result=0
    #....print num1,num2