#include<iostream>
#include <stdio.h>
#include<string>
using namespace std;
const int maxn=1005;
string add(string x,string y)
{
  string ans ;
  int lenx = x.length();
  int leny = y.length();
  if(lenx<leny)
  {
    for(int i = 1;i<=leny-lenx;i++)
      x = "0"+x;
  }
  else
  {
    for(int i = 1;i<=lenx-leny;i++)
      y = "0"+y;
  }
  lenx = x.length();
  int cf = 0;
  int temp;
  for(int i = lenx-1;i>=0;i--)
  {
    temp = x[i] - '0' + y[i] - '0'+cf;
    cf = temp/10;
    temp%=10;
    ans = char('0'+temp)+ans;
  }
  if(cf!=0)
    ans = char(cf+'0')+ans;
  return ans;
}

int main(){
  string num[1005];
  num[0] = "0";
  num[1] = "1";
  num[2] = "2";
  for(int i = 3;i<=1000;i++){
    num[i] = add(num[i-1],num[i-2]);
  }
  int n;
  while(cin>>n){
        cout<<num[n]<<endl;
  }
  return 0;
}