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

#define DONT_KNOW "I_dont_know"

void printIDontKnow()
{
    printf("%s", DONT_KNOW);
    exit(0);
}

int examB_q2(char **s, int n);

//Do not change these functions
void free_string_arr(char **arr, int n)
{
    for (int i = 0; i < n; ++i)
    {
        free(arr[i]);
    }
    free(arr);
}

bool read_string(char **s)
{
    int len;
    if (scanf("%d", &len) != 1)
    {
        return false;
    }
    *s = malloc((len + 1) * sizeof(char));
    if (!*s)
    {
        return false;
    }
    if (scanf("%s", *s) != 1)
    {
        free(*s);
        return false;
    }
    return true;
}

int main(void)
{
    // uncomment next line if you don't know the answer
    // printIDontKnow();

    int n;
    if (scanf("%d", &n) != 1)
        return 1;
    char **arr = malloc(sizeof(char *) * n);
    if (!arr)
        return 1;
    for (int i = 0; i < n; i++)
    {
        if (!read_string(arr + i))
        {
            free_string_arr(arr, i);
            return 1;
        }
    }
    printf("%d", examB_q2(arr, n));
    free_string_arr(arr, n);
    return 0;
}

bool compareStringsLexi(char *checkable, char *later,
    int *letterLen, char *letter)
{
    int lengthCheck = strlen(checkable), lengthLater = strlen(later); // O(m)

    int val = strcmp(checkable, later);
    if (val <= 0) // checkable is before(or equal to) later
    {
        if (*letter != later[0])
        {
            (*letter) = later[0];
            (*letterLen) = lengthLater;
        }
        else
        {
            if ((*letterLen) > lengthLater)
            {
                (*letterLen) = lengthLater;
            }
        }

        if (lengthCheck <= lengthLater)
        {
            return true;
        }
    }
    else // checkable is after later
    {
        if (lengthCheck == lengthLater && (*letterLen) >= lengthLater)
        {
            return true;
        }

        if (lengthCheck > lengthLater && (*letterLen) > lengthLater)
        {
            return true;
        }
    }

    return false;
}

bool compareStringsLength(char *shorter, char *longer)
{
    int cmp = strcmp(shorter, longer);
    if (cmp <= 0)
    {
        return true;
    }

    return false;
}

/*
 * This function checks if the length-ordered array can be rearanged to be
 * also a lexi ordered array.
 *
 * input:
 *  1. char **arr: the array of strings
 *  2. int n: the length of the string array
 * output(int):
 *  1 if you can order and 0 if you can not
*/
int examB_q2(char **arr, int n)
{
    if (n < 1)
    {
        return 1;
    }

    int indexOfLargestLexi = 0;
    int currentLetterShortest = strlen(arr[0]);
    char currentLetter = arr[0][0];

    for (int i = 1; i < n; i++)
    {
        int lengthI = strlen(arr[i]), lengthI1 = strlen(arr[i - 1]);
        bool lexi = compareStringsLexi(
            arr[indexOfLargestLexi], arr[i],
            &currentLetterShortest, &currentLetter
        );
        bool len = compareStringsLength(arr[i - 1], arr[i]);
        if (lexi)
        {
            indexOfLargestLexi = i;
            if (!len && (lengthI1 > lengthI))
            {
                return 0;
            }
        }
        else
        {
            return 0;
        }
    }

    return 1;
}