#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;

class Number {
  public:
    Number() {}
    Number(string n) : num(n) {num = string(num.rbegin(), num.rend());}
    void show();
    void operator=(string n) {*this = Number(n);}
    friend string operator+(const Number& left, const Number& right);
    int strLen() {return num.length();}
    string str() {return num;}
  private:
    string num;
};

void Number:: show() {
  for (string::reverse_iterator it = num.rbegin(); it != num.rend(); ++it) {
    cout << *it;
  }
  cout << endl;
}

string
operator+(const Number& left, const Number& right) {
  string ans, st, lg;
  if (left.num.length() > right.num.length()) {
    lg = left.num;
    st = right.num; }
  else {
    st = left.num;
    lg = right.num;
  }
  int add;
  int fuck = 0;
  for (size_t i = 0; i < st.length(); ++i) {
    add = st[i] + lg[i] + fuck - 2 * '0';
    fuck = add / 10;
    add %= 10;
    ans += (add + '0');
  }
  for (size_t i = st.length(); i < lg.length(); ++i) {
    add = lg[i] + fuck -'0';
    fuck = add / 10;
    add %= 10;
    ans += (add + '0');
  }
  if (fuck) ans += '1';
  ans = string(ans.rbegin(), ans.rend());
  return ans;
}

Number fuckit[201];
int main() {
  fuckit[1] = "1";
  fuckit[2] = "2";
  for (int i = 3; i<= 200; ++i) {
    fuckit[i] = fuckit[i-2] + fuckit[i-1];
  }
  int n;
  while (scanf("%d", &n) != EOF) {
    fuckit[n].show();
  }
  return 0;
}