cf1152D

#include<bits/stdc++.h>
#define forn(i, n) for (int i = 0 ; i < int(n) ; i++)
#define fore(i, s, t) for (int i = s ; i < (int)t ; i++)
#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define pf2(x,y) printf("%d %d
",x,y)
#define pf(x) printf("%d
",x)
#define each(x) for(auto it:x)  cout<<it<<endl;
#define pii pair<int,int>
#define sc(x) scanf("%d",&x)
using namespace std;
typedef long long ll;
const int maxn=1e4+5;
const int maxm=2e5+5;
const int inf=1e9;
const int mod = 1000 * 1000 * 1000 + 7;
int add(int a, int b) {
    return (a + b >= mod ? a + b - mod : a + b);
}
const int max_n = 1001;
pair<int, bool> dp[2 * max_n][2 * max_n];
int main() {
	int n;
   	sc(n);
    n *= 2;
    dp[0][0] = make_pair(0, true);
    for (int len = 1; len <= n; ++len) {
        for (int bal = 0; bal <= n; ++bal) {
            // (len, bal) -> (len - 1, bal + 1)
            // (len, bal) -> (len - 1, bal - 1)
            int sum = 0;
            bool has = false;
            if (bal != 0) {
                sum = add(sum, dp[len - 1][bal - 1].first);
                has = has or dp[len - 1][bal - 1].second;
            }
            if (bal + 1 <= len - 1) {
                sum = add(sum, dp[len - 1][bal + 1].first);
                has = has or dp[len - 1][bal + 1].second;
            }
            if (has)
                dp[len][bal] = make_pair(add(sum, 1), false);
            else
                dp[len][bal] = make_pair(sum, true);
        }
    }
    cout << dp[n][0].first << "
";
    return 0;
}