#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ double fz,fzo=2,fm,fmo=1,sum=2,n; cin>>n; for(int i=2;i<=n;i++){ fm=fzo; fz=fzo+fmo; sum+=fz/fm; fmo=fm; fzo=fz; } cout<<sum; return 0; }