long long atoll(char *str){
long long result = 0;
int negative=0;

while (*str == ' ' || *str == '\t')
str++;
if (*str == '+')
str++;
else if (*str == '-') {
negative = 1;
str++;
}

while (*str >= '0' && *str <= '9') {
result = (result*10) - (*str++ - '0');
}

return negative ? result : -result;
}