#include <cstdio>
const int MAXN = 2000;
int n, f[MAXN][MAXN], s[MAXN+1], ans;
inline int max(int a, int b) {
	return a>b ? a : b;
}
int main() {
	freopen("xoinc.in", "r", stdin);
	freopen("xoinc.out", "w", stdout);
	scanf("%d", &n);
	for(int i=n; i>0; i--)
		scanf("%d", s+i);
	for(int i=1; i<=n; i++)
		s[i] += s[i-1];
	for(int i=1; i<=n; i++)
		for(int j=1; j<=n; j++) {
			f[i][j] = f[i][j-1];
			if(i-(j*2-1) >= 0)
				f[i][j] = max(f[i][j], s[i] - f[i-(j*2-1)][j*2-1]);
			if(i-(j*2) >= 0)
				f[i][j] = max(f[i][j], s[i] - f[i-(j*2)][j*2]);
		}
	ans = f[n][1];
	printf("%d\n", ans);
	return 0;
}