#include <bits/stdc++.h>
using namespace std;
int main()
{
int n = 0,ret=0,i=0;
int arr[100];
arr[0] = 1;
arr[1] = 1;
while (~scanf("%d", &n))
{
if (n <= 2)
ret = 1;
else
{
for (i = 2; i < n; i++)
arr[i] = arr[i - 1] + arr[i - 2];
ret = arr[n - 1];
}
printf("%d", ret);
}
return 0;
}