#include <string.h>

int strcmp(const char *s1, const char *s2)
{
	while (*s1 != '\0' && *s2 != '\0' && *s1 == *s2) {
		s1 += 1;
		s2 += 1;
	}
	return ((unsigned char) *s1 - (unsigned char) *s2);
}