#include <iostream>
#include "stack.h"

using namespace std;

int fib(int n) {
  Stack <int> s;
  int sum = 0;

  //first "call"
  s.push(n);

  while(!s.isEmpty()) {
    n = s.pop();
    if(n == 0 || n == 1){
      sum+=1;  //do something
      continue;
    }

    //recursive cases
    s.push(n-2);
    s.push(n-1);
  }

  return sum;
}


int main(void) {
  int n;
  START:
  cin >>n;

  cout <<fib(n) << endl;
  goto START;
  
  return 0;
}