a = float(input('a = '))
c = input()
b = float(input('b = '))
if c == "-" :
////print (a-b)
elif c == "/" :
////if c != "0" :
////////print (a/b)
////else :
////////print("Деление на ноль!")
elif c == "*":
////print(a*b)
elif c == "mod":
////print (a % b)
elif c == "pow":
////print(a ** b)
elif c == "div":
////print(a // b)
elif c == "+":
////print(a+b)
все '/' ето 1 пробел
1) 1+3=4 (2)
2) 4*2=8 (1)
3) 8*2=16 (1)
4) 16+3=19 (2)
5) 19*2=38 (1)
В ответе пишешь : 21121