text: #include <iostream>
  #include <iomanip>
  #include <cmath>
  #include <string>
  #include <cstring>
  using namespace std;
  int GetNum(int n){
      if (n == 1)
          return 1;
      else if (n == 2)
          return 2;
      else
          return GetNum(n - 1) + GetNum(n - 2);
  }
  int main(){
      int n;
      cin >> n;
      cout << GetNum(n);
      //system("pause > nul");
      return 0;
  }