求修改

#include<map>
#include<iostream>
#include<utility>
#include<string>
#include<vector>
#include<set>
using namespace std;
int main()
{
multimap<string,set<string> >works;
string author;
string author_work;
multimap<string,set<string> >::iterator iworks;
bool order1=true;
while(order1){
cout<<"输入作者姓名：";
cin>>author;
if(((iworks=works.find(author))!=works.end())){
char order2;
cout<<"作者名字已经存在，继续添加作品？(Y/N）:";
begin1:cin>>order2;
if(order2=='y'||order2=='Y'){
cout<<"输入要添加的作品,按ctrl+z退出"<<endl;
while(cin>>author_work){
if(iworks->second.count(author_work))
cout<<"作品已存在，无需重复添加"<<endl;
else
iworks->second.insert(author_work);
}
cin.clear();
}
else if(order2=='n'||order2=='N')
continue;
else{
cout<<"命令输入错误，请重新输入：";
goto begin1;
}
}
else{
set<string> new_author_works;
cout<<"输入要添加的作品,按ctrl+z退出:";
while(cin>>author_work){
if(new_author_works.count(author_work))
cout<<"作品已存在，无需重复添加"<<endl;
else
new_author_works.insert(author_work);
}
cin.clear();
pair<string,set<string> > works_type(author,new_author_works);
works.insert(works_type);
}
char result;
cout<<"继续添加吗？(Y/N)";
begin2:cin>>result;
if(result=='y'||result=='Y')
continue;
else if(result=='n'||result=='N')
order1=false;
else{
cout<<"命令输入错误，请重新输入：";
goto begin2;
}
}
cout<<"输入要删除的作者：";
while(cin>>author){
if((iworks=works.find(author))!=works.end())
works.erase(iworks);
else
cout<<"作者不存在！"<<endl;
}
cin.clear();
char cval;
if(works.empty())
cout<<"容器为空"<<endl;
else{
for(iworks=works.begin();iworks!=works.end();++iworks){
set<string>::iterator iauthor_work;
cval=iworks->first[0];
cout<<"Author Names Beginning with" <<"'"<<cval<<"':";
cout<<"作者:"<<iworks->first<<" 作品：";
for(iauthor_work=iworks->second.begin();iauthor_work!=iworks->second.end();++iauthor_work)
cout<<*iauthor_work<<" ";
++iworks;
while(cval==iworks->first[0]){
cout<<"作者:"<<iworks->first<<" 作品：";
for(iauthor_work=iworks->second.begin();iauthor_work!=iworks->second.end();++iauthor_work)
cout<<*iauthor_work<<" ";
cout<<endl;
++iworks;
}
--iworks;
}
}
return 0;
}
能运行成功，并成功实现所需要的功能，但在最后跳出错误