1069.c

#include <stdio.h>
#include <string.h>

int main()
{
	char s[1000][21] = {{0}}, line[21];
	int M, N, S, m, count = 0, r = 0;

	scanf("%d %d %d", &M, &N, &S);

	for (m = 0, S--; m < M; m++) {
		scanf("%s", line);
		if (m == S + count * N + r) {
			int flag = 1;
			for (int i = 0; i < count && flag; i++)
				if (!strcmp(s[i], line)) {
						flag = 0;
						r++;
						break;
				}
			if (flag)
				strcpy(s[count++], line);
		}
	}

	for (int i = 0; i < count; i++)
		printf("%s\n", s[i]);
	if (!count)
		printf("Keep going...");

	return 0;
}