#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <limits.h>


void itoa(int n, char s[]);

/* passes arg to itoa or INT_MIN if no arg is given */
int main(int argc, char *argv[])
{
    int n;
    if (argc < 2) {
        printf("expected : %d\n", INT_MIN);
        n = INT_MIN;
    } else
        n = atoi(argv[1]);

    char s[(int)log10(INT_MAX) + 3];
    itoa(n, s);
    printf("%s\n", s);
    return 0;
}

void reverse(char *s);

/* itoa: convert n to characters in s */
void itoa(int n, char s[])
{
    int i;
    unsigned absn = (n < 0) ? -n : n; /* handles INT_MIN */

    i = 0;
    do {
        s[i++] = absn % 10 + '0';
    } while ((absn /= 10) > 0);

    if (n < 0)
        s[i++] = '-';
    s[i] = '\0';
    reverse(s);
}

/* reverse: reverses string s in place */
void reverse(char *s)
{
    char c, *s2;
    for (s2 = s + strlen(s) - 1; s < s2; s++, s2--)
        c = *s, *s = *s2, *s2 = c;
}