更新s，s有两种情况，一个是s+=n，另一个是之前领过奖的不能领，s+=1

#include<iostream>
#include<string>
#include<cstring>
#include<map>
using namespace std;
int m, n, s;
bool f = false;
map<string, int>mp;
int main()
{
    scanf("%d%d%d", &m, &n, &s);
    getchar();
    for (int i = 1; i <= m; i++)
    {
        string str;
        getline(cin, str);
        if (i == s&&mp.find(str) != mp.end())s = s + 1;
        if (i == s&&mp.find(str)==mp.end())
        {
            mp[str] = 1;
            cout <<"      "<< str << endl;
            f = true;
            s += n;
        }
    }
    if (f == false)printf("Keep going...\n");
    return 0;
}