why is it numeric(0)?

hello,everyone. I have one question:

example 1

x=numeric(0)
y=5
print(x+y)

numeric(0)
 
example 2

x=numeric(1)
y=5
print(x+y)

[1] 5

why the print(x+y)  is numeric(0) at the first example, but the result is 0
at the second example? 


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