int/string conversion

string itos(int n)
{
    string tmp;
    if(n < 0)
    {
        tmp = "-";
        n = -n;
    }
    if(n > 9)
        tmp += itos(n / 10);
    tmp += n % 10 + 48;
    return tmp;
}

int stoi(string s)
{
    int tmp = 0;
    unsigned i = 0;
    bool m = false;
    if(s[0] == '-')
    {
        m = true;
        i++;
    }
    for(; i < s.size(); i++)
        tmp = 10 * tmp + s[i] - 48;
    return m ? -tmp : tmp;
}