1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 #include<iostream>
 5 #define inf 999999999
 6 //using namespace std;
 7 const int MAX = 1000005;
 8 int max(int a,int b)
 9 {
10     return a>b?a:b;
11 }
12 int a[MAX];
13 int left[MAX];
14 int right[MAX];
15 int main()
16 {
17     int n,m,i,j;
18     while(scanf("%d%d",&m,&n)!=EOF)
19     {
20         memset(a,0,sizeof(a));
21         memset(left,0,sizeof(left));
22         memset(right,0,sizeof(right));
23         for(i=1;i<=n;i++)
24             scanf("%d",&a[i]);
25         long long count;
26         for(i=1;i<=m;i++)
27         {
28             count=-inf;
29             for(j=i;j<=n;j++)
30             {
31                 left[j]=max(left[j-1],right[j-1])+a[j];
32                 right[j-1]=count;
33                 if(left[j]>count)
34                     count=left[j];
35             }
36         }
37         printf("%I64d\n",count);
38     }
39     return 0;
40 }