1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <vector>
 7 #include <queue>
 8 #include <stack>
 9 #include <map>
10 #include <string>
11 #include <set>
12 #define ms(a,b) memset((a),(b),sizeof((a)))
13 using namespace std;
14 typedef long long LL;
15 const double EPS = 1e-8;
16 const int INF = 2e9;
17 const LL LNF = 2e18;
18 const int MAXN = 1e6+10;
19 
20 int a[MAXN];
21 int last_max[MAXN], all_max[2][MAXN];
22 
23 int main()
24 {
25     int n, m;
26     while(scanf("%d%d",&m, &n)!=EOF)
27     {
28         for(int i = 1; i<=n; i++)
29             scanf("%d", &a[i]);
30 
31         ms(all_max, 0);
32         ms(last_max, 0);
33 
34         int id = 0;
35         for(int i = 1; i<=m; i++)
36         {
37             id = !id;
38             all_max[id][i-1] = -INF;
39             for(int j = i; j<=n; j++)
40             {
41                 last_max[j] = max(last_max[j-1], all_max[!id][j-1]) + a[j];
42                 all_max[id][j] = max(all_max[id][j-1], last_max[j]);
43             }
44         }
45         printf("%d\n", all_max[id][n]);
46     }
47     return 0;
48 }