tj

#include<iostream>
#include<cmath>
#include<algorithm>
#include<queue>
#include<stack>
#include<vector>
#include<cstdio>
#include<unordered_map>
#define ll long long
using namespace std;
unordered_map<ll,ll> mp;
ll solve(ll n) {
	if(mp[n]) return mp[n];
	if(n<=2) return 1;
	return mp[n]=solve(n-1)+solve(n-2);
}
int main() {
	ll n;
	cin>>n;
	cout<<solve(n);
}