Bessie has gone to the mall's jewelry store and spies a charm bracelet. Of course, she'd like to fill it with the best charms possible from the N (1 ≤ N ≤ 3,402) available charms. Each charm i in the supplied list has a weight Wi (1 ≤ Wi ≤ 400), a 'desirability' factor Di (1 ≤ Di ≤ 100), and can be used at most once. Bessie can only support a charm bracelet whose weight is no more than M (1 ≤ M ≤ 12,880).
Given that weight limit as a constraint and a list of the charms with their weights and desirability rating, deduce the maximum possible sum of ratings.
有N件物品和一个容量为V的背包。第i件物品的重量是c[i]，价值是w[i]。求解将哪些物品装入背包可使这些物品的重量总和不超过背包容量，且价值总和最大。
输入输出格式
输入格式：-
Line 1: Two space-separated integers: N and M
- Lines 2..N+1: Line i+1 describes charm i with two space-separated integers: Wi and Di
- Line 1: A single integer that is the greatest sum of charm desirabilities that can be achieved given the weight constraints
输入输出样例
输入样例#1：
4 6 1 4 2 6 3 12 2 7
输出样例#1：
23
01背包：
#include<cstdio>
#include<iostream>
#include<algorithm>
using namespace std;
int n,m;
int f[12880];
int main()
{
int i,j,c,w;
scanf("%d%d",&n,&m);
for (i=1; i<=n; ++i)
{
scanf("%d%d",&c,&w);
for (j=m; j>=c; --j)
f[j]=max(f[j],f[j-c]+w);
}
printf("%d",f[m]);
}