print("Hello, my name is calculator! And what about you? ")
name = input( "My name is: ")
name1 = "Andrew"
if name != name1:
    print('Error')
    exit(0)
what = input( "what we doing? (+,-,*,/,**,%,//): " )
a = float( input( "Write first number: ") )
b = float( input( "Write second number: ") )
c = None

f = {
'+':lambda x,y:x+y,
'-':lambda x,y:x-y,
'*':lambda x,y:x*y,
'/':lambda x,y:x/y,
'**':lambda x,y:x**y,
'%':lambda x,y:x%y,
'//':lambda x,y:x//y,
}

try:
    print(f[what](a,b))
except:
    print('error')