I need a userinterface with one big button

def add(a, b):
  return a + b

def main():
  a = int(input("Enter a number: "))
  b = int(input("Enter a number: "))
  c = add(a, b)
  print("The sum of the two numbers is", c)

main()

A:

You can use the built-in sum() function to sum up a list