#include<stdio.h> 
int Fibon1(int n)
{
 if (n == 1 || n == 2)
 {
  return 1;
 }
 else
 {
  return Fibon1(n - 1) + Fibon1(n - 2);
 }
}
int main()
{
 int n = 0;
 int ret = 0;
 scanf("%d", &n);
 ret = Fibon1(n);
 printf("ret=%d", ret);
 return 0;
}