#include<stdio.h>
#include<string.h>
FILE*fin=fopen("aib.in","r");
FILE*fout=fopen("aib.out","w");
#define nm 100005
#define zero(x)((x^(x-1))&x)
int aib[nm],s[nm],n,m;
int query(int poz)
{
    int ans=0;
    while(poz>0)
    {
      ans+=aib[poz];
      poz-=zero(poz);
    }
    return ans;
}
void update(int poz,int nr)
{
     while(poz<=n)
     {
       aib[poz]+=nr;
       poz+=zero(poz);
     }
}
int main()
{
    int i,op,st,dr,mij,nr,poz,a,b,sum;
    fscanf(fin,"%d%d",&n,&m);
    memset(aib,0,sizeof(aib));
    for(i=1;i<=n;i++)
    {
      fscanf(fin,"%d",&s[i]);
      update(i,s[i]);
    }
    for(i=1;i<=m;i++)
    {
      fscanf(fin,"%d",&op);
      if(op==0)
      {
        fscanf(fin,"%d%d",&poz,&nr);
        update(poz,nr-s[poz]);
        s[poz]=nr;
      }
      if(op==1)
      {
        fscanf(fin,"%d%d",&a,&b); 
        fprintf(fout,"%d\n",query(b)-query(a-1));
      }
      if(op==2)
      {
        fscanf(fin,"%d",&nr);
        st=0;dr=n;
        while(st<dr)
        {
          mij=(st+dr)/2;
          sum=query(mij);
          if(sum==nr)
          {
            st=mij;
            break;
          }
          else if(sum<nr) st=mij+1;
               else dr=mij-1;
        }
        fprintf(fout,"%d\n",st);
      }
    }
    fclose(fin);
    fclose(fout);
    return 0;
}