#include<stdio.h> |
#include<math.h> |
void main() |
{ |
double i,s,n,sum=0; |
i=1; |
s=2; |
scanf ( "%lf" ,&n); |
while (i<=n) |
{ |
sum=sum+s; |
s=s+2* pow (10,i); |
i++; |
} |
printf ( "sum=%lf\n" ,sum); |
} |