#include<iostream>

 #include<stdio.h>

 #define MAXN  10000001

 using namespace std;

 int a[MAXN];

 void give_set();

 int min(int i,int j);

 int main()

 {

     //freopen("acm.acm","r",stdin);

     give_set();

     int num;

     while(cin>>num)

     {

         cout<<a[num-]<<endl;

     }

 }

 void give_set()

 {

     a[] = ;

     int m;

     int len = ;

     int x;

     int y;

     x = ;

     y = ;

     while(len < MAXN)

     {

         m = min(*a[x]+,*a[y]+);

         if(m == *a[x]+)

             ++ x;

         if(m == *a[y]+)

             ++ y;

         a[len++] = m;

     }

 }

 int min(int a,int b)

 {

     return a < b ? a : b;

 }