#include <stdio.h>
#include <math.h>
f
(n
){return n
?n
*f
(n
-1):1;}float c
(n
,x
)float x
;{return n
?c
(n
-1,x
)+pow(-1,n
)*pow(x
,2*n
)/f
(2*n
):1;}
int main(void)
{
return 0;
}
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