C :

#include "stdio.h"
#include "string.h"
int n,m;
int a[25],b[25],f[30001];
int main()
{
	int i,j;
	while(scanf("%d%d",&m,&n)!=EOF)
	{
		memset(f,0,sizeof(f));
		for(i=0;i<n;i++)
			scanf("%d%d",&a[i],&b[i]);
		for(i=0;i<n;i++)
		{
			for(j=m;j>=a[i];j--)
				if(f[j-a[i]]+a[i]*b[i]>f[j])
					f[j]=f[j-a[i]]+a[i]*b[i];
		}
		printf("%d\n",f[m]);
	}
	return 0;
}

C++ :

#include<iostream>
#include<cstdio>
using namespace std;

int i[31],w[31],c[30001];

int main()
{
	//freopen("test.in","r",stdin);
	int m,n;
	cin>>m>>n;
	for (int j=1;j<=n;j++)
		cin>>w[j]>>i[j];
	
	for (int j=1;j<=n;j++)
		for (int k=m;k>=w[j];k--)
			if(c[k]<c[k-w[j]]+i[j]*w[j])
				c[k]=c[k-w[j]]+i[j]*w[j];
		
	cout<<c[m];
	
	return 0;
}

Pascal :

var n, w, u, v, i, j, ans : longint;
    f : array[0 .. 30010]of longint;
   
begin
  readln(w, n);
  for i := 1 to n do
  begin
    read(u, v);
    for j := w-u downto 0 do
    begin
      if f[j]+u*v>f[j+u] then f[j+u] := f[j]+u*v;
      if f[j+u] > ans then ans := f[j+u];
    end;
  end;
  writeln(ans);
end.