/* header files */ 
#include <stdio.h>
#include <stdlib.h> 
#include <math.h> /* main */ 
int main( void ) 
{ char s[] = " sno ";
char empty[] = ""; 
if ( isnan(nan(s)) )
{ 
	printf(" nan(s): NaN\n ");
} 
if ( isnan(nan(empty)) ) 
{ 
	printf(" nan(empty): NaN\n ");
} 
if ( isnan(nan( NULL )) )
{ 
	printf(" nan(NULL): NaN\n ");
} 
return EXIT_SUCCESS ;
}