Contest1205/C不要11.cpp

#include <bits/stdc++.h>
using namespace std;
const int MOD = 100000007;
int main() {
  int F[100002][2] = {0};
  F[1][0] = 1, F[1][1] = 1;
  F[2][0] = 2;
  F[2][1] = 1;
  int n;
  cin >> n;
  for (int i = 3; i <= n; i++) {
    F[i][0] = (F[i - 1][0] + F[i - 1][1]) % MOD;
    F[i][1] = F[i - 1][0];
  }
  cout << (F[n][0] + F[n][1]) % MOD << endl;
 
  return 0;
}