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


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

/* passes args to itoa or INT_MIN if no arg is given */
int main(int argc, char *argv[])
{
    int n, w;
    n = (argc > 1) ? atoi(argv[1]) : INT_MIN;
    w = (argc > 2) ? atoi(argv[2]) : (int)log10(abs(n)) + 1 + (n < 0);

    if (w < 0) {
        printf("error : invalid width %d\n", w);
        return 1;
    }

    char s[w+1];
    itoa(n, s, w);
    printf("%s\n", s);
    return 0;
}

void reverse(char *s);

/* itoa: convert n to characters (base 10) in s, pads with leading spaces
 * to width w, truncates (left part) string of n if its is wider than w */
void itoa(int n, char s[], unsigned w)
{
    int i = 0;
    unsigned un = (n < 0) ? -n : n;

    /* handle zero */
    if (!n && w)
        s[i++] = '0';
    
    /* handle number */
    for (; i < w && un > 0; un /= 10, i++) {
        s[i] = un % 10 + '0';
    }
    /* handle sign */
    if (n < 0 && i < w)
        s[i++] = '-';
    /* pad with spaces */
    while (i < w)
        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;
}