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

// An extremely simple allocation system.
// Memory must be freed in the reverse order it was allocated.
#define ALLOCSIZE 10000

static char allocbuf[ALLOCSIZE];
static char *allocp = allocbuf;

char *alloc(int n) {
    if (allocbuf + ALLOCSIZE - allocp >= n) {
        allocp += n;
        return allocp - n;
    } else {
        return NULL;
    }
}

void afree(char *p) {
    if (p >= allocbuf && p < allocbuf + ALLOCSIZE) {
        allocp = p;
    }
}

#define MAXLINES 5000

int readlines(char* lineptr[], int nlines);

void writelines(char* lineptr[], int nlines);

void qsort(char* lineptr[], int left, int right);

int main() {
    int nlines;
    char* lineptr[MAXLINES];
    if ((nlines = readlines(lineptr, MAXLINES)) >= 0) {
        qsort(lineptr, 0, nlines-1);
        writelines(lineptr, nlines);
        return 0;
    } else {
        fprintf(stderr, "error: input too big to sort\n");
        return 1;
    }
}

#define MAXLEN 1000

int z_getline(char*, int);
char* alloc(int);

int readlines(char* lineptr[], int maxlines) {
    int len; 
    int nlines = 0;
    char* p;
    char line[MAXLEN];
    while ((len = z_getline(line, MAXLEN)) > 0) {
        if (nlines >= maxlines || (p = alloc(len)) == NULL) {
            return -1;
        } else {
            line[len-1] = '\0'; // delete newline
            strcpy(p, line);
            lineptr[nlines++] = p;
        }
    }
    return nlines;
}

void writelines(char* lineptr[], int nlines) {
    for (int i=0; i<nlines; i++)
        printf("%s\n", lineptr[i]);
}

void qsort(char* v[], int left, int right) {
    int i, last;
    void swap(char* v[], int i, int j);
    if (left >= right) {
        return;
    }
    swap(v, left, (left+right)/2);
    last = left;
    for (i=left+1; i<=right; i++) {
        if (strcmp(v[i], v[left]) < 0) {
            swap(v, ++last, i);
        }
    }
    swap(v, left, last);
    qsort(v, left, last-1);
    qsort(v, last+1, right);
}

void swap(char* v[], int i, int j) {
    char* temp = v[i];
    v[i] = v[j];
    v[j] = temp;
}


/* getline:  read a line into s, return length */
int z_getline(char s[], int lim) {
    int c, i;
    for (i=0; i<lim-1 && (c=getchar())!=EOF && c!='\n'; ++i) {
        s[i] = c;
    }
    if (c == '\n') {
        s[i] = c;
        ++i;
    }
    s[i] = '\0';
    return i;
}