编译器错误。令牌之前的预期';'

//this application implements use of a simple set
//program does data insertion,searching, and deletion
//program will represent a set of keys
//a user can add a key, delete a key, and check for duplicate keys
#include<iostream>
#include<set>
#include<string>
using namespace std;
int main()
{
string key, answer,answer2;
int i;
std::set<std::string> Keyring;
//prompts user to insert elements in set
for(i = 0; i < 5; i++)
{
cout<<"nInsert Key " <<i+1<<" Onto Key Ring. Use _ For Spaces"<<endl;
cin >>key;
Keyring.insert(key);
}
//shows resulting key ring
cout<<"nHere is Completed Key Ringn"<<endl;
for(std::set<std::string>::iterator it=Keyring.begin(); it !=Keyring.end(); it++) //the '<' operator keeps UNIQUE elements in sorted order
{
std::cout<<" "<<"n"<< *it; 
}

//Set Deletion and Addition
cout<<"nWould You Like to Add or Delete From Key Ring?"<<endl;
cout<<"nType add or delete"<<endl;
cin>>answer;
if(answer=="add")
{
cout<<"nAdd Another Key. Use _ For Spaces"<<endl;
cin>>key;
Keyring.insert(key);
    if(Keyring.insert(key).second) //checks to see if key already present in set
    {
    cout<<key<<" Successful Addition!"<<endl;
    }   
    else if(!Keyring.insert(key).second)
    {
    cout<<" Duplicate Key Can't Be Added!"<<endl;
    }
}
else(answer=="delete")
{
cout<<"nDelete A Key. Use _ For Spaces"<<endl;
cin>>key;
Keyring.erase(key);
cout<<"nNew Keyring"<<endl;
}
for(std::set<std::string>::iterator it=Keyring.begin(); it !=Keyring.end(); it++)
{
std::cout<<" "<<"n"<< *it;
}
cout<<"nKeyring size is "<<Keyring.size()<<endl;
//Set Searching
cout<<"nWant To Search For A Key y/n?"<<endl;
cin>>answer2;
if(answer2=="y")
{
cout<<"nSearch For A Key. Use _ For Spaces"<<endl;
cout<<"nWhere Is My..."<<endl;
cin>>key; cout<<" Key?"<<endl;
}
std::set<std::string>::iterator it=Keyring.find(key);
if(it !=Keyring.end())
{
cout<<key<<"nFound!"<<endl;
}
else
{
cout<<key<<"nNot Found :("<<endl;
}
return 0;
}

我由于这个错误而无法运行程序：[错误]预期';'在" {"令牌之前。问题始于"集合添加和删除"部分。问题在于该部分中的大型IF-ELSE语句，在其他语句启动的地方。我一直在寻找一个小时，令人沮丧！编译器说应该有一个';在"否则"语句行之前，一切都很好。我检查了嵌套的文档，以便避免此问题。需要帮助！