/* Note:Your choice is C IDE */
#include "stdio.h"
float p(int n,int x )
{
if(n==0)
return (1);
else if(n==1)
return (x);
else
return ((2*n-1)*p(n-1,x)*x-(n-1)*p(n-2,x))/n;
}
void main()
{
int n,x,i;
float t;
printf("please input n and x:\n");
scanf("%d %d",&n,&x);
t=p(n,x);
printf("the result is %f.\n",t);
}