def plus(num1,num2):
    return num1+num2

def minus(num1,num2):
    return num1-num2

def multiply(num1,num2):
    return num1*num2

def divide(num1,num2):
    if num2!=0:
        return num1/num2
    else:
        print("0으로 나누면 안됨니다")
        return -1
