#include <stdio.h>
#include <ctype.h>
#include <limits.h>

int myatoi(char *instr) {
	if (instr == NULL) {
		return 0;
	}

	while (isspace((unsigned char)*instr)) {
		instr++;
	}

	int sign = 1;
	if (*instr == '+') {
		instr++;
	} else if (*instr == '-') {
		sign = -1;
		instr++;
	}

	long result = 0;
	while (*instr >= '0' && *instr <= '9') {
		int digit = *instr - '0';

		if (sign > 0) {
			if (result > (LONG_MAX - digit) / 10) {
				return INT_MAX;
			}
		} else {
			if (-result < (LONG_MIN + digit) / 10) {
				return INT_MIN;
			}
		}

		result = result * 10 + digit;
		instr++;
	}

	return (int)(result * sign);
}

int main() {
printf("myatoi(\"1\") = %d\n", myatoi("1"));
    printf("myatoi(\"42\") = %d\n", myatoi("42"));
    printf("myatoi(\"-105\") = %d\n", myatoi("-105"));
    printf("myatoi(\"   -12abc34\") = %d\n", myatoi("   -12abc34"));
    printf("myatoi(\"9999999999999\") = %d (overflow)\n", myatoi("9999999999999"));

    return 0;
}