Why can't I use the input function in the def function in python?

Question

this is the example that we are given:

def print_sum_twice(x, y):
print(x + y)
print(x + y)

print_sum_twice(5, 8)

why can't I write it this way..

def print_sum_twice():
x = input("give the first number: ")
y = input("give the 2nd number: ")
print(x+y)
print(x+y)

print_sum_twice()

it give me an error, why?

Answer 1

input is in string type so you must convert it to integer like: x = int(input())

Answer 2

In fact, what @Vukan told is true, but it stills should not gives an error as strings can be added.
Did you put two lines as input ? If not, this is why it failed. Sololearn ask for ALL inputs at the beginning of the program