15 lines
183 B
C++
15 lines
183 B
C++
#include<cstdio>
|
|
int n; double now,res;
|
|
int main()
|
|
{
|
|
scanf("%d",&n);
|
|
now=420000.0/n;
|
|
for(int i=1;i<=n;i++)
|
|
{
|
|
res+=now;
|
|
now*=(1-0.5/i);
|
|
}
|
|
printf("%.2lf\n",res);
|
|
return 0;
|
|
}
|