#include <cstdio>
#include <string>

int n,v1[100],v2[100],v3[100];

void add(int A[], int B[], int C[])  
{  
      int i, t = 0;  
      for (i=1; i<=A[0] || i<=B[0] || t; i++, t/=10)  
              C[i] = (t += A[i] + B[i]) % 10;  
      C[0] = i - 1;  
}  

int main()
{
  freopen("nunta.in","r",stdin);
  freopen("nunta.out","w",stdout);
  
  scanf("%d",&n);
  
  v1[0] = 1, v1[1] = 1;
  v2[0] = 1, v2[1] = 1;
  v3[0] = 1, v3[1] = 1;
  
  
  for(int i=2; i<=n; i++)
  {
    add(v1,v2,v3);
    memcpy(v1,v2, sizeof v2);
    memcpy(v2,v3, sizeof v3);
  }
  
  for(int i=v3[0]; i; --i)
    printf("%d",v3[i]);
  return 0;
}