// Fibonacci - version récursive
#include<stdio.h>
#include<stdlib.h>

unsigned int fibo(unsigned int n)
{
  if(n == 0 || n == 1)
    return 1;
  else
    return fibo(n-1) + fibo(n-2);
} // fibo()

int main()
{
  int n = 0;

  scanf("%u", &n);

  printf("%u\n", fibo(n));

  return 0;
} // main()