#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  vector<int> a(m);
  for (int i = 0; i < m; i++) {
    cin >> a.at(i);
  }
  vector<int> f(n);
  f[0] = 1;
  f[1] = 2;
  for (int i = 2; i < n; i++) {
    f[i] = f[i - 1] + f[i - 2];
  }
  cout << f.at(n - 1) << endl;
}
