del_el_tree

void del(int number){
        tree_struct *poi=find(number);

        if(poi->left==NULL && poi->right==NULL){//dziala
            if(poi==top){
                delete top;
                top=NULL;
            }
            else{
                tree_struct *father_poi=find_father(number);
                if(father_poi->left==poi)
                    father_poi->left=NULL;
                else
                    father_poi->right=NULL;
                delete poi;
            }
        }
        else if(poi->left!=NULL && poi->right!=NULL){
            tree_struct *prev_poi=previous(number);
            if(poi->left==prev_poi){
                if(prev_poi->left!=NULL)
                    poi->left=prev_poi->left;
                else
                    poi->left=NULL;
                poi->number=prev_poi->number;
                delete prev_poi;
            }
            else{
                tree_struct *father_prev=find_father(prev_poi->number);
                poi->number=prev_poi->number;

                if(prev_poi->left!=NULL){
                    father_prev->right=prev_poi->left;
                }
                else
                    father_prev->right=NULL;
                delete prev_poi;
            }

        }
        else{
            if(poi==top){
                tree_struct *poi_help;
                if(poi->left!=NULL){
                    poi_help=top->left;
                    delete top;
                    top=poi_help;
                }
                else{
                    poi_help=top->right;
                    delete top;
                    top=poi_help;
                }
            }
            else{
                tree_struct *father_poi=find_father(number);
                if(poi->left!=NULL){
                    if(father_poi->left==poi){
                        father_poi->left=poi->left;
                    }
                    else{
                        father_poi->right=poi->left;
                    }
                }
                else{
                    if(father_poi->left==poi){
                        father_poi->left=poi->right;
                    }
                    else{
                        father_poi->right=poi->right;
                    }
                }
                delete poi;
            }
        }
    }