#include "bits/stdc++.h" using namespace std; typedef long long ll; typedef pair pii; typedef pair pll; const int INF = 1e9; const ll LINF = 1e18; inline ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; } inline ll lcm(ll a, ll b) { return a / gcd(a, b)*b; } template ostream& operator << (ostream& out,const pair& o){ out << "(" << o.first << "," << o.second << ")"; return out; } template ostream& operator << (ostream& out,const vector V){ for(int i = 0; i < V.size(); i++){ out << V[i]; if(i!=V.size()-1) out << " ";} return out; } template ostream& operator << (ostream& out,const vector > Mat){ for(int i = 0; i < Mat.size(); i++) { if(i != 0) out << endl; out << Mat[i];} return out; } template ostream& operator << (ostream& out,const map mp){ out << "{ "; for(auto it = mp.begin(); it != mp.end(); it++){ out << it->first << ":" << it->second; if(mp.size()-1 != distance(mp.begin(),it)) out << ", "; } out << " }"; return out; } /* 問題文============================================================ ================================================================= 解説============================================================= Nが小さい場合について、愚直に答えを確かめると (test関数) OEISでヒットする >> https://oeis.org/A001250 ページ下部の方に、O(n^2)でとくやり方が乗っているので、その通りに実装するだけ ================================================================ */ bool kadomatsu(int a,int b,int c){ return (ba && b>c);} void test(){ for(int i = 1; i < 10;i++){ int cnt = 0; vector v(i); iota(v.begin(),v.end(),1); do{ bool ok = true; for(int j = 0; j < i-2; j++){ if(kadomatsu(v[j], v[j+1], v[j+2])) continue; ok = false; break; } cnt+=ok; }while(next_permutation(v.begin(),v.end())); cout << i << " : " << cnt << endl; } } const ll MOD = 1e9+7; ll calc(ll n){ ll ret = 1; map A = {{-1,0},{0,2}}; ll k = 0,e = 1; for(int i = 0; i <= n;i++){ ll Am = 0; e = -e; for(int j = 0; j <= i; j++){ ll& a = A[k]; Am += a; if(Am >= MOD) Am -= MOD; a = Am; k += e; } } if(n&1) ret = A[n/2]; else ret = A[-n/2]; return ret; } ll solve(){ ll res = 0; ll N; cin >> N; if(N <= 2) return 0; res = calc(N); return res; } int main(void) { cin.tie(0); ios_base::sync_with_stdio(false); //test(); cout << solve() << endl; return 0; }