#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int main()
{
    int total_people,shuttle_capacity,asker_position;
    char names_line[1000];
    if (scanf("%d %d %d",&total_people, &shuttle_capacity, &asker_position)!=3)
    {
        printf("Invalid input\n");
        return 0;
    }
    getchar();
    if (fgets(names_line,sizeof(names_line),stdin)) == NULL
    {
        printf("Invalid input\n");
        return 0;
    }
    if (total_people < 10 || total_people > 200 || shuttle_capacity < 1 || shuttle_capacity > 20 || asker_position < 1 || asker_position > total_people)
    {
        printf("Invalid input\n");
        return 0;
    }
    int name_count = 0;
    char*token=strtok(names_line,"\n");
    while(token != NULL)
    {
        name_count++;
        token=strtok(NULL,"\n");
    }
    if (name_count != total_people)
    {
        printf("Invalid input\n");
        return 0;
    }
    int rounds=(asker_position-1)/shuttle_capacity+1;
    printf("%d\n",rounds);
    return 0;
}