a = int(input("First number? "))
b = int(input("Second number? "))
op = input("Operation (plus, minus, times, divide)? ")

if op == "plus":
    print(a + b)
elif op == "minus":
    print(a - b)
elif op == "times":
    print(a * b)
elif op == "divide":
    print(a / b)
else:
    print("Unknown operation")