#include <stdio.h>
#include <memory.h>
#define MaxM 23
struct STATIONS
{
	int st,en;
	int odr;
}order[MaxM];
int cap;
int n,m;
int i,j;
int peo[MaxM];
int earn,ans;
int a[MaxM];
int opt[MaxM];
int GetData()
{
	scanf("%d%d%d",&cap,&n,&m);
	if (cap==0) return 0;
	for (i=1;i<=m;i++) scanf("%d%d%d",&order[i].st,&order[i].en,&order[i].odr);
	opt[m]=order[m].odr*(order[m].en-order[m].st);
	for (i=m-1;i>=1;i--)
	{
		opt[i]=opt[i+1]+order[i].odr*(order[i].en-order[i].st);
	}
	return 1;
}
int Backward(int ix)
{
	int jx;
	for (jx=order[ix].st;jx<order[ix].en;jx++) peo[jx]=peo[jx]-order[ix].odr;
	earn=earn-order[ix].odr*(order[ix].en-order[ix].st);

	return 0;
}
int Forward(int ix)
{
	int jx;
	for (jx=order[ix].st;jx<order[ix].en;jx++) peo[jx]=peo[jx]+order[ix].odr;
	earn=earn+order[ix].odr*(order[ix].en-order[ix].st);

	return 0;
}
int Judge(int ix)
{
	int jx;
	if (a[ix])
	{
		if (ix<=m-1 && earn+order[ix].odr*(order[ix].en-order[ix].st)+opt[ix+1]<=ans) return 0;
		for (jx=order[ix].st;jx<order[ix].en;jx++) if (peo[jx]+order[ix].odr>cap) return 0;
	}
	else if (ix<=m-1 && earn+opt[ix+1]<=ans) return 0;
	return 1;
}
int main()
{
	while (GetData())
	{
		ans=0;
		memset(peo,0,sizeof(peo));
		earn=0;
		i=1;
		a[i]=-1;
		while (i>0)
		{
			if (i>m)
			{
				if (earn>ans) ans=earn;
				i--;
				if (a[i]) Backward(i);
			}
			else
			{
				a[i]++;
				if (a[i]>1)
				{
					i--;
					if (a[i]) Backward(i);
				}
				else if (Judge(i)) 
				{
					if (a[i]) Forward(i);
					i++;
					a[i]=-1;
				}
			}
		}
		printf("%d\n",ans);
	}
	return 0;
}