#include <iostream>
#include <fstream>
#define MAXn 100000;

using namespace std;ifstream f("kfib.in");
ofstream g("kfib.out");
int mach[100000000];


 unsigned k,n;

int fib(unsigned n){
   float f;
   if(mach[n]!=0) return mach[n];
   if(n<=2) f=1;
   else f=fib(n-1)+fib(n-2);
   mach[n]=f;
   return f;
}


int main()
{f>>k;

 g<<fib(k);

    return 0;
}