문제
풀이
#include <iostream>
#include <vector>
using namespace std;
void solve(void) {
int n;
cin >> n;
vector<long long> a(n+1);
a[0] = a[1] = 1;
for (int i=2; i<=n; i++) {
a[i] = a[i-1] + a[i-2];
}
cout << a[n] * 2 + a[n-1] * 2;
}
int main(void) {
ios::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}