#include<iostream.h>
#include<stdlib.h>
int main()
{
    int n;
    char f,q,l;
    while(cin>>n)        //题目没有给出结束条件
    {
        if(n>1000000 || n<=0)    //辨断n的界线
            exit(0);
        char ar[26]={'a',};    //初始化，无确定的值的变量为0
        //输入和赋值
        for(int i=0;i<n;i++)
        {
            cin>>f>>q>>l;
            if(ar[l-97]) ar[f-97]=f;
            else ar[f-97]=0;
        }
        int j=0;
        int temp=0;
        //辨断变量是否有确定的值
        while(j<26)
        {
            if(ar[j])
            {
                temp=1;
                break;
            }
            j++;
        }
        //输出
        if(temp)
        {
            cout<<ar[j];
            j=j+1;
            while(j<26)
            {
                if(ar[j])
                    cout<<" "<<ar[j];//从题目输出格式可知输出的最后一位不能有空格
                j++;
            }
            cout<<endl;
        }
        else
            cout<<"none"<<endl;
    }
    return 0;
}

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