def add(a,b):
    return a + b
def subtract(a,b):
    return a - b    
def multiply(a,b):
    return a * b
def divide(a,b):
    if b == 0:
        return "Error: Division by zero"
    return a / b
def main():
    print("Welcome to DataCal!")
    print("Select operation:")
    print("1. Add")
    print("2. Subtract")
    print("3. Multiply")
    print("4. Divide")
    choice = input("Enter choice(1/2/3/4): ")
    num1 = float(input("Enter first number: "))
    num2 = float(input("Enter second number: "))
    if choice == '1':
        print(f"{num1} + {num2} = {add(num1,num2)}")
    elif choice == '2':
        print(f"{num1} - {num2} = {subtract(num1,num2)}")
    elif choice == '3':
        print(f"{num1} * {num2} = {multiply(num1,num2)}")
    elif choice == '4':
        print(f"{num1} / {num2} = {divide(num1,num2)}")
    else:
        print("Invalid input")
    