include stdio include stdlib include math int main void int float eps

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(void)
{ int n=1;
 float eps=1e-5,x,c=x-1,z=n*x,a=c/z,sum=0;
 
 scanf("%f", &x);
 
 while(fabsf(a) > eps)
 { c*=c;
  x*=x;
  sum+=a;
  n++;
}
    
         printf("%f\n", sum);


  
  system("PAUSE");	
  return 0;
}