hdu 1702 ACboy needs your help again

#include <iostream>
#include <string>
#include <queue>
#include <stack>
using namespace std;
void que_solve(int n)
{
queue<int>Q;
char s[10];
int a;
while(n--)
{
cin>>s;
if(!strcmp(s, "IN"))
{
cin>>a;
Q.push(a);
}
else if(!strcmp(s, "OUT"))
{
if(Q.empty())
cout<<"None"<<endl;
else
{
cout<<Q.front()<<endl;
Q.pop();
}
}
}
}
void sta_solve(int n)
{
stack<int>S;
char s[10];
int a;
while(n--)
{
cin>>s;
if(!strcmp(s, "IN"))
{
cin>>a ;
S.push(a);
}
else if(!strcmp(s, "OUT"))
{
if(S.empty())
cout<<"None"<<endl;
else
{
cout<<S.top()<<endl;
S.pop();
}
}
}
}
int main()
{
int n;
while(cin>>n)
{
while(n--)
{
int m;
char str[100];
cin>>m>>str;
if(!strcmp(str,"FIFO"))
que_solve(m);
else if(!strcmp(str,"FILO"))
sta_solve(m);
else
cout<<"error"<<endl;
}
}
return 0;
}