#include
#include
int main(void)
{
int n;
double i,j,k;
double res = 0;
printf("please input n:");
scanf("%d",&n);
i = 1;
j = 1;
while(n--)
{
k = i;
i = k + j;
j = k;
res += i / j;
}
printf("The result is %lf\n",res);
return 0;
}