ANSI scanf dropping sign bit?

[martin at clubmed.hf.intel.com.ogi.edu]

Why does the following program when linked to an ANSI standard library
produce the following:

input: 90000000

output: 10000000

input: 80000000

output: 00000000

#include <stdio.h>

int main()
{
	unsigned int	input;

	scanf("%x", &input);

	printf("%x\n", input);
}

It appears that sign bit is being dropped.  I have run this program on
Sys V.3.2 and it retains the sign bit, but this is not ANSI compliant.

Any hints...
thanks

                          
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