The new ITone 6 has been released recently and George got really keen to buy it. Unfortunately, he didn‘t have enough money, so George was going to work as a programmer. Now he faced the following problem at the work.
Given a sequence of n integers
p1,?p2,?...,?pn. You are to choose
k pairs of integers:
[l1,?r1],?[l2,?r2],?...,?[lk,?rk] (1?≤?l1?≤?r1?<?l2?≤?r2?<?...?<?lk?≤?rk?≤?n; ri?-?li?+?1?=?m),?
in such a way that the value of sum 
is maximal possible. Help George to cope with the task.
Input
The first line contains three integers n,
m and k
(1?≤?(m?×?k)?≤?n?≤?5000). The second line contains
n integers p1,?p2,?...,?pn
(0?≤?pi?≤?109).
Output
Print an integer in a single line — the maximum possible value of sum.
Sample test(s)
Input
5 2 1 1 2 3 4 5
Output
9
Input
7 1 3 2 10 7 18 5 33 0
Output
61
题意：将一个长度为n的序列，分成k段长度为m的子序列，求这k个子序列和的最大值
思路：dp[i][j]表示是前i个数选出j段的最大值，显然有不选这个数，和考虑这个数的两种情况。而考虑这个数的话，因为连续性也只会增加以这个数为结尾的m序列
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
typedef long long ll;
using namespace std;
const int maxn = 5100;
ll num[maxn], sum[maxn], dp[maxn][maxn];
ll n, m, k;
int main() {
cin >> n >> m >> k;
for (int i = 1; i <= n; i++) {
cin >> num[i];
sum[i] = sum[i-1] + num[i];
}
for (int i = m; i <= n; i++)
for (int j = k; j >= 1; j--)
dp[i][j] = max(dp[i-1][j], dp[i-m][j-1]+sum[i]-sum[i-m]);
cout << dp[n][k] << endl;
return 0;
}