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

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


 unsigned k,n,i;

int fi(unsigned n){
   float f;
   for(i=1;i<=n;++i){
   if(n<=2) f=1;
   else f=fib[n-1]+fib[n-2];
   fib[n]=f;}
   return fib[n];
}


int main()
{f>>k;

 g<<fi(k);

    return 0;
}