void F(RangeMinimumQuerry RMQ, int l, int r)
{
RMQ.Querry(l, r);
int s = RMQ.C;
Add(l, s, s, r, RMQ.D);
if (s != l)
{
F(RMQ, l, s - 1);
}
if (s != r)
{
F(RMQ, s + 1, r);
}
}
void Calc()
{
string[] str = Console.ReadLine().Split(' ');
N = int.Parse(str[0]);
int M = int.Parse(str[1]);
long[] A = new long[N];
str = Console.ReadLine().Split(' ');
for (int i = 0; i < N - 1; i++)
{
A[i + 1] = A[i] + int.Parse(str[i]);
}
long[,] B = new long[N, M];
for (int i = 0; i < N; i++)
{
str = Console.ReadLine().Split(' ');
for (int j = 0; j < M; j++)
{
B[i, j] = int.Parse(str[j]);
}
}
Map = new long[N, N];
for (int j = 0; j < M; j++)
{
RangeMinimumQuerry RMQ = new RangeMinimumQuerry(N, this);
for (int i = 2 * N - 2; i >= 0; i--)
{
if (i >= RMQ.segf)
{
RMQ.X[i] = B[RMQ.ToPoint(i), j];
RMQ.Y[i] = RMQ.ToPoint(i);
}
else
{
int sl = i * 2 + 1;
int sr = i * 2 + 2;
if (RMQ.X[sl] > RMQ.X[sr])
{
RMQ.X[i] = RMQ.X[sl];
RMQ.Y[i] = RMQ.Y[sl];
}
else
{
RMQ.X[i] = RMQ.X[sr];
RMQ.Y[i] = RMQ.Y[sr];
}
}
}
F(RMQ, 0, N - 1);
}
long max = 0;
for (int i = 0; i < N; i++)
{
for (int j = 0; j < N; j++)
{
Map[i, j] += (i == 0 ? 0 : Map[i - 1, j]) + (j == 0 ? 0 : Map[i, j - 1]) - ((i == 0 || j == 0) ? 0 : Map[i - 1, j - 1]);
}
}
for (int i = 0; i < N; i++)
{
for (int j = i; j < N; j++)
{
max = Math.Max(max, Map[i, j] + A[i] - A[j]);
}
}
sb.Append(max + "\n");
}