#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <conio.h>
#include <string.h>

int numline(char *fp) {
	char buff;
	int coun = 0;
	while ((buff = fgetc(fp)) != EOF) {
		if (buff == '\n') {
			++coun;
		}
	}
	return coun + 1;
}

char missline(char *fp, int num) {
	char buff;
	int coun = 0;
	while ((buff = fgetc(fp)) != EOF && coun < num) {
		if (buff == '\n') {
			++coun;
		}
	}
	return buff;
}

int main() {

	FILE  *fp;
	int counter = 0, num = 0, c = 0;
	char *mode = "r";
	char utility[10], name[10];

	while (counter == 0) {
		printf(">");
		scanf("%s %s", utility, name);
		if ((c = getchar()) == ' ')
			scanf("%d", &num);
		if (strcmp(utility, "./tail") != 0) {
			printf("Error: wrong utility\n");
			if ((fp = fopen(name, mode)) == NULL)
				printf("Error: file isn't available\n");
			if (c != '\n')
				while ((c = getchar()) != '\n');
		}
		else if ((fp = fopen(name, mode)) == NULL) {
			printf("Error: file isn't available\n");
			if (c != '\n')
				while ((c = getchar()) != '\n');
		}
		else
			++counter;
	}
	if (num == 0) {
		counter = 0;
		char arr[100];
		int i = 0;
		while ((arr[i] = fgetc(fp)) != EOF && counter < 5) {
			if (arr[i] == '\n') {
				arr[i] = '\0';
				printf("%s\n", arr);
				i = 0;
				++counter;
			}
			else i++;
		}
		arr[i] = '\0';
		printf("%s", arr);
	}
	else {
		char buff = 0;
		counter = numline(fp);
		fseek(fp, 0, SEEK_SET);
		char arr[100];
		int i = 0;
		buff = missline(fp, counter - num);
		counter = 0;
		arr[i] = buff;
		++i;
		while ((arr[i] = fgetc(fp)) != EOF) {
			if (arr[i] == '\n') {
				arr[i] = '\0';
				printf("%s\n", arr);
				i = 0;
			}
			else i++;
		}
		arr[i] = '\0';
		printf("%s\n", arr);
	}
	_getch();
	fclose(fp);
}