using System.Text.RegularExpressions;

using System;

using System.Collections.Generic; 

​

public class Solution {

    public static void Main(){

        Console.Write("Type in your input: ");

        string str = Console.ReadLine();

        int ansInint = MyAtoi(str);

        Console.WriteLine("Your input was :{0} and converting it to int :{1} =" ,str,ansInint);

    }

    public static int MyAtoi(string str) {

        Console.WriteLine("---------------------------");

        if (str =="" || str == " ") return 0;

        Dictionary<char,int> dict = new Dictionary<char,int>()

        {

            {'0',0},

            {'1',1},

            {'2',2},

            {'3',3},

            {'4',4},

            {'5',5},

            {'6',6},

            {'7',7},

            {'8',8},

            {'9',9},

            {'-',10},

            {'+',-1},

            {'.',12}

        };

        string trimmedStr = str.Trim(); // remove whitespaces

        Console.WriteLine("trimmedStr: "+trimmedStr);

        Console.WriteLine("trimmedStr.Length: "+trimmedStr.Length);

        // forced logic checks for +- -+ and single .

        if (trimmedStr == "" || trimmedStr == "+")return 0;

        if (trimmedStr[0] == '-' && trimmedStr.Length == 1) return 0;

        if (trimmedStr[0] == '+' && trimmedStr[1] == '-' || trimmedStr[0] == '-' && trimmedStr[1] == '+' || trimmedStr[0] == '.') return 0;

        // if first character in string is an alphabet return 0

        int alphaB = 0;

        if (dict.TryGetValue(trimmedStr[0], out alphaB))

            {

                alphaB = 0;

            } 

                else 

            {

                return 0;

            }

        if (dict[trimmedStr[0]]== -1 ){

            if (!dict.ContainsKey(trimmedStr[1])) return 0; // return 0 if unwanted value on '1' index of string

            if (dict[trimmedStr [1]] == -1) return 0;

          trimmedStr = Regex.Replace(trimmedStr, "[^0-9.-^a-z ]", "");  // remove + sign on string

        } 

        Console.WriteLine("Reg trimmedStr:"+trimmedStr);

        int numCounter= 0; // the counter for the numbers in the string till it reaches unwanted character

        foreach (char s in trimmedStr)

        {

            if (dict.ContainsKey(s)){

                if (numCounter > 0 && dict[s] == 10 && numCounter < trimmedStr.Length -1 ) 

                { 

                    return 0;

                }

                else if (numCounter > 0 && dict[s] == -1)

                {

                    break;

                }

                else{

                    numCounter++;

                 }

                //numCounter ++;

                Console.WriteLine("NumCounter:"+numCounter);

                continue;

            }

            else {

                break;

            }

        }

        Console.WriteLine("TrimmedStr length after check:"+trimmedStr.Length);

        if (trimmedStr.Length != 0) {

            if (trimmedStr[trimmedStr.Length-1] == '-') numCounter--;    

        }

        Console.WriteLine("NumCounter:"+numCounter);

        trimmedStr = trimmedStr.Substring(0,numCounter);

        bool negative = false;       

        bool deci = false;

        int[] allInts = new int [trimmedStr.Length]; 

        int c = 0; // counter for int array

        foreach (char s in trimmedStr){

            if(dict.ContainsKey(s)&& dict[s]!= 10 &&dict[s]!= 12) allInts[c++]= dict[s];

            if(dict[s] == 10) negative = true;

            if(dict[s] == 12) deci = true; 

        }

        double ans = 0; // final answer in double 

        int power = 1; // counter for the 10^power maths to readd the ints to their original order

        int lengthCheck = negative ? trimmedStr.Length - 1 : trimmedStr.Length; // if the number is negative -1 in string length

        if (deci) lengthCheck --; // decimal 

        for (int n = 0; n< lengthCheck ; n++){

            int x = allInts[n];

            ans += x/(Math.Pow(10,power)); // to insert the numbers in the same order as the string adding each int in decimal format

            power++;

        }

        ans *= Math.Pow(10,power-1); // removing the decimal format and rearranging to required format

        if (negative) ans *= -1; 

        if (deci) ans /= Math.Pow(10,c-1); 

        Console.WriteLine("ans b4 ret: "+ans);

        if (ans>= Int32.MaxValue ) ans = Int32.MaxValue;

        if (ans <= Int32.MinValue ) ans = Int32.MinValue;

        ans = Convert.ToInt32(ans);

        Console.WriteLine("ans after intMAx: "+ans);

        return (int)ans;

    }

}