#include <iostream> using namespace std; #define N 100010 #define ll long long ll s[N], l[N], r[N]; int n, k; void init() { for (int i = k; i <= n; i++) { l[i] = max(l[i - 1], s[i] - s[i - k]); } for (int i = n - k + 1; i > 0; i--) { r[i] = max(r[i + 1], s[i + k - 1] - s[i - 1]); } } int main() { scanf("%d%d", &n, &k); for (int i = 1; i <= n; i++) { scanf("%lld", &s[i]); s[i] += s[i - 1]; } init(); ll res = 1e18; for (int i = 1; i <= n - k + 1; i++) { if (i < k) { res = min(res, r[i + k]); continue; } if (i >= k && i + 2 * k - 1 <= n) { res = min(res, max(l[i - 1], r[i + k])); continue; } if (i + 2 * k - 1 > n) { res = min(res, l[i - 1]); } } printf("%lld", res); return 0; }