#include<cstdio>
#include<cstring>
#include<algorithm>
#define ll long long
using std::max;
using std::swap;
const int N=500010;
struct node
{int l,r,lsum,rsum,msum,sum;
}e[N<<2];
#define ls ro<<1
#define rs ro<<1|1
inline void pushup(int ro)
{e[ro].sum=e[ls].sum+e[rs].sum;e[ro].lsum=max(e[ls].lsum,e[ls].sum+e[rs].lsum);e[ro].rsum=max(e[rs].rsum,e[rs].sum+e[ls].rsum);e[ro].msum=max(max(e[ls].msum,e[rs].msum),e[ls].rsum+e[rs].lsum);
}
void build(int ro,int l,int r)
{e[ro].l=l,e[ro].r=r;if(l==r){int x;scanf("%d",&x);e[ro].lsum=e[ro].rsum=e[ro].msum=e[ro].sum=x;return;}int mid=(l+r)>>1;build(ls,l,mid);build(rs,mid+1,r);pushup(ro);
}
void change(int ro,int x,int p)
{if(e[ro].l==e[ro].r){if(e[ro].l==x) e[ro].lsum=e[ro].rsum=e[ro].msum=e[ro].sum=p;return;}int mid=(e[ro].l+e[ro].r)>>1;if(x<=mid) change(ls,x,p);else change(rs,x,p);pushup(ro);
}
node query(int ro,int l,int r)
{node tl,tr,tt;if(e[ro].l==l&&e[ro].r==r) return e[ro];int mid=(e[ro].l+e[ro].r)>>1;if(r<=mid) return query(ls,l,r);else if(mid<l) return query(rs,l,r);else {tl=query(ls,l,mid);tr=query(rs,mid+1,r);tt.msum=max(max(tl.msum,tr.msum),tl.rsum+tr.lsum);tt.lsum=max(tl.lsum,tl.sum+tr.lsum);tt.rsum=max(tr.rsum,tr.sum+tl.rsum);        return tt;}
}
int main()
{int n,m;scanf("%d %d",&n,&m);build(1,1,n);
//    for(int i=1;i<=20;i++)
//    printf("std:: %d %d %d %d %d %d\n",e[i].l,e[i].r,e[i].lsum,e[i].rsum,e[i].msum,e[i].sum);int dp,l,r;for(int i=1;i<=m;i++){scanf("%d %d %d",&dp,&l,&r);if(dp==1) {if(l>r) swap(l,r);node ans=query(1,l,r);printf("%d\n",ans.msum);}else {change(1,l,r);
//            for(int i=1;i<=20;i++)
//            printf("std:: %d %d %d %d %d %d\n",e[i].l,e[i].r,e[i].lsum,e[i].rsum,e[i].msum,e[i].sum);
        }}return 0;
}