#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cmath>

using namespace std;

int i,j;
int a[10001];
int k,l;
int m,n,max1,o,mark;
char pp;

int main()
{
	freopen("happya.in","r",stdin);
	freopen("happya.out","w",stdout);
	scanf("%d%d",&n,&m);
	for (i=1;i<=m;i++)
	{
		scanf("%c",&pp);
		if (pp='\n') scanf("%c",&pp);
		if (pp=='I')
		{
			scanf("%d%d%d",&k,&l,&o);
			for (j=k;j<=l;j++) a[j]=a[j]+o;
		}
		else
		{
			max1=0;
			scanf("%d%d",&k,&l);
			for (j=k;j<=l;j++)
			{
				if (max1<a[j]) 
				{
					max1=a[j];
					mark=j;
				}
			}
			printf("%d\n",max1);
			a[mark]=0;			
		}
	}
	return 0;
}