1/1+2/1+3/2+5/3+......+(n)

[MiaoMiao]

#include <stdio.h>
double
foo(int n)
{
int i;
double result=1,u=1,d=1;
if(1==n)return 1;
for(i=1;i<n;++i){
double t=d;
d=u;
u=d+t;
result+=u/d;
}
return result;
}

int
main(void)
{
int n;
while(EOF!=(fscanf(stdin,"%d",&n))){
fprintf(stdout,"%.3lf\n",foo(n));
}
return 0;
}