#include <stdio.h>
#include <vector>
#define minim(a,b)((a>b)?b:a)
#define maxim(a,b)((a>b)?a:b)
#define NMax 100000
using namespace std;
int n,m,x,y,z,val,pos,arb[4*NMax],start,finish,suma;
std::vector< int > a;
void _update(int nod,int left,int right)
{
    if(left == right)
    {
        arb[nod] = arb[nod] + val;
        return;
    }

    int mij = ((left+right)>>1);
    if(pos <= mij)_update((nod<<1),left,mij);
    else _update(((nod<<1)|1),mij+1,right);
    arb[nod] = arb[(nod<<1)]+arb[((nod<<1)|1)];
}
void _query(int nod,int left,int right)
{
    if( start <= left && right <= finish )
    {
        suma = suma + arb[nod];
        return;
    }

    int mij = ((left+right)>>1);
    if( start <= mij )_query((nod<<1),left,mij);
    if( mij < finish )_query(((nod<<1)|1),mij+1,right);
}
int main()
{
    freopen("aib.in","r",stdin);
    freopen("aib.out","w",stdout);
    scanf("%d %d",&n,&m);
    for(int i=1;i<=n;++i)
    {
        scanf("%d",&x);
        a.push_back(x);
        pos = i;val = x;
        _update(1,1,n);
    }
    for(int i=1;i<=m;++i)
    {
        scanf("%d %d",&x,&y);
        if(x==0)
        {
            scanf("%d",&z);
            pos = y;val = z;
            _update(1,1,n);
        }
        else if(x==1)
        {
            scanf("%d",&z);
            suma = 0;
            start = y;finish = z;
            _query(1,1,n);
            printf("%d\n",suma);
        }
        else if(x==2)
        {
            int p=1,u=n,mijloc;
            bool gasit = false;
            while(p<=u)
            {
                suma = 0;
                start = p;finish = u;
                _query(1,1,n);
                mijloc = ((u+p)>>1);
                if(suma>y)u = mijloc;
                else if(suma<y)p = mijloc+1;
                else if(suma==y)
                {
                    gasit = true;
                    break;
                }
            }
            printf("%d\n",u);
        }
    }
    return 0;
}