solution

#include<iostream>
#include<string>
#include<map>
using namespace std;
int main(){
	int n, m, s, loop = 0, have = 0;
	string id;
	map<string, int> mp;
	cin >> m >> n >> s;
	for(int i = 1; i <= m; i++){//编号从1开始
		cin >> id;
		if(i == s) {
			cout << id << endl;
			mp[id] = have = 1;
		}
		if(i > s) loop++;
		if(loop >= n){//到达间隔&&没有中过奖，才能列入中奖名单，否则继续后延
			if(!mp.count(id)){//mp.count(key)键值存在返回1，否则返回0
				cout << id << endl;
				mp[id] = have = 1;
				loop = 0;
			}
		}
	}
	if(!have) cout << "Keep going...";//没人中奖
	return 0;
}