// Fibonacci - programmation dynamique
#include <stdio.h>
#include <stdlib.h>

unsigned int fibo(unsigned int n)
{
  unsigned int *memo;

  memo = (unsigned int *)malloc((n+1)*sizeof(unsigned int));

  memo[0] = memo[1] = 1;
  for(int k = 2; k <= n; k++)
    memo[k] = memo[k-1] + memo[k-2];

  int result = memo[n];

  free(memo); memo = NULL;

  return result;
} // fibo()

int main()
{
  int n = 0;

  scanf("%u", &n);

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

  return 0;
} // main()