int myAtoi(string a) {
int n=a.length();
int i=0;
bool neg=0;
while(i<n&&a[i]==' ')
i++;
if(i==n)
return 0;
if(a[i]=='+'||a[i]=='-'||a[i]>='0'&&a[i]<='9')
{
    if(a[i]=='-'||a[i]=='+')
    {
        if(a[i]=='-')
        neg=1;
        i++;
    }
    int ans=0;
    while(i<n&&a[i]>='0'&&a[i]<='9')
    {
        int prev=ans;
        ans=(ans*10)+a[i]-'0';
        if(ans%10!=(a[i]-'0'))
        {
            if(neg)
            return INT_MIN;
            else
            return INT_MAX;
        }
        i++;
    }
    if(neg)
    return -ans;
    else
    return ans;
}
else
{
    return 0;
}
}