#include<cstdio>

 #include<cctype>

 #include<vector>

 #include<algorithm>

 inline int getint() {

     char ch;

     while(!isdigit(ch=getchar()));

     int x=ch^'';

     while(isdigit(ch=getchar())) x=(((x<<)+x)<<)+(ch^'');

     return x;

 }

 const int N=,Q=,logN=;

 class FotileTree {

     private:

         unsigned int left[(N<<)+Q*logN],right[(N<<)+Q*logN];

         std::vector<int> val;

         void push_up(const int p) {

             val[p]=std::max(val[left[p]],val[right[p]]);

         }

     public:

         unsigned int root[Q];

         unsigned int newnode() {

             val.push_back();

             return val.size()-;

         }

         void build(const int p,const int b,const int e) {

             if(b==e) {

                 val[p]=getint();

                 return;

             }

             int mid=(b+e)>>;

             build(left[p]=newnode(),b,mid);

             build(right[p]=newnode(),mid+,e);

             push_up(p);

         }

         unsigned int modify(const int p,const int b,const int e,const int x,const int y) {

             unsigned int new_p=newnode();

             if(b==e) {

                 val[new_p]=y;

                 return new_p;

             }

             int mid=(b+e)>>;

             if(x<=mid) left[new_p]=modify(left[p],b,mid,x,y),right[new_p]=right[p];

             if(x>mid) right[new_p]=modify(right[p],mid+,e,x,y),left[new_p]=left[p];

             push_up(new_p);

             return new_p;

         }

         int query(const int p,const int b,const int e,const int l,const int r) {

             if((b==l)&&(e==r)) return val[p];

             int mid=(b+e)>>;

             int ans=;

             if(l<=mid) ans=std::max(ans,query(left[p],b,mid,l,std::min(mid,r)));

             if(r>mid) ans=std::max(ans,query(right[p],mid+,e,std::max(mid+,l),r));

             return ans;

         }

 };

 FotileTree t;

 int main() {

     freopen("longterm_segtree.in","r+",stdin);

     freopen("longterm_segtree.out","w+",stdout);

     int n=getint(),q=getint(),ver=;

     t.build(t.root[++ver]=t.newnode(),,n);

     while(q--) {

         int op=getint(),k=getint(),x=getint(),y=getint();

         if(!op) printf("%d\n",t.query(t.root[k],,n,x,y));

         if(op) t.root[++ver]=t.modify(t.root[k],,n,x,y);

     }

     fclose(stdin),fclose(stdout);

     return ;

 }