HDU-1024

#include <iostream>
#include <memory.h>
#include <string>
#include <istream>
#include <sstream>
#include <vector>
#include <stack>
#include <algorithm>
#include <map>
#include <queue>
#include <math.h>
#include <cstdio>
using namespace std;

typedef long long LL;

const int MAXN = 1e6 + 10;
const int INF = 0x7fffffff;

int a[MAXN];
int dp[MAXN];
int Max[MAXN];

int main()
{
    int n, m, mmax;


    while (~scanf("%d%d", &m, &n))
    {
        for (int i = 1;i <= n;i++)
            scanf("%d", &a[i]);

        memset(dp,0, sizeof(dp));
        memset(Max,0, sizeof(Max));

        for (int i = 1;i <= m;i++)
        {
            mmax = -INF;
            for (int j = i;j <= n;j++)
            {
                dp[j] = max(dp[j - 1], Max[j - 1]) + a[j];
                Max[j - 1] = mmax;
                mmax = max(mmax, dp[j]);
            }
        }
        printf("%d\n", mmax);
    }

    return 0;
}