#include using namespace std; #define rep(i, n) for (int i = 0; i < (int)(n); i++) #define llong long long int main() { int n; cin >> n; vector dp(n+1); dp[0] = 1; rep(i, n) { if(i + 1 <= n) dp[i+1] += dp[i]; if(i + 2 <= n) dp[i+2] += dp[i]; } cout << dp[n] << endl; }