PAT basic 1069

#include <iostream>#include <map>using namespace std;int main() {    int m, n, s;    scanf("%d%d%d", &m, &n, &s);    string str;    map<string, int> mapp;    bool flag = false;    for (int i = 1; i <= m; i++) {        cin >> str;        if (mapp[str] == 1) s = s + 1;        if (i == s && mapp[str] == 0) {            mapp[str] = 1;            cout << str << endl;            flag = true;            s = s + n;        }    }    if (flag == false) cout << "Keep going...";    return 0;}