#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
#define N 210
int main()
{
   int n;
   while(scanf("%d",&n)!=EOF)
   {
       int s[N][N];
       int i,j,l;
       s[1][1]=1;
       s[2][1]=2;
       for(i=3,l=1;i<=n;i++)
       {
           int k=0;
           for(j=1;j<=l;j++)
           {
               s[i][j]=s[i-1][j]+s[i-2][j]+k;
               k=s[i][j]/10;
               s[i][j]%=10;
           }
           while(k)
           {
               s[i][++l]=k%10;
               k/=10;
           }
       }
       for(i=l;i>=1;i--)
        printf("%d",s[n][i]);
       printf("\n");
   }
   return 0;
}