洛谷P6457

#include <bits/stdc++.h>
using namespace std;
int n, a[303], f[303][303], ans;
bool vis[303][303];

// 取 l 或取 r 
int dfs(int l, int r) {
	if (r - l == n+1)
		return 0;
	if (vis[l][r])
		return f[l][r];
	vis[l][r] = true;
	if (l == r)
		return f[l][r] = -dfs(l-1, r+1) + a[l]%2;
	else 
		return f[l][r] = max(-dfs(l-1, r) + a[l]%2, -dfs(l, r+1) + a[r]%2);
}

int main() {
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
		a[n+i] = a[2*n+i] = a[i];
	}
	for (int i = n+1; i <= 2*n; i++) {
		memset(vis, 0, sizeof vis);
		if (dfs(i, i) > 0)
			ans++;
	}
	cout << ans << endl;
	return 0;
}