#include<iostream> int main(){ double a,b,c,d,max; a=1; c=1; scanf("%lf",&b); while(1<=b){ d=c+1;//d=2 c=c/d;//c=1/2 d++;//d+1 a=a+c;//a+0.5 b=b-2;//b-2 } printf("%.3lf",a); return 0; }