#include<stdio.h>
void main(void)
{
     double x, a, b, s;
     int i, n;
     printf("n="); scanf("%d", &n); /*近似項数の入力*/
     printf("x="); scanf("%lf", &x); /*xの入力*/
     a = x - 1.0;
     b = 1.0;
     s = a / b;
     for (i = 2; i <= n; i++) {
         a = -a*(x-1.0);
         b = i;
         s = s + a / b;
     }
     printf("log(x)=%lf\n", s); /*結果の表示*/
}