import java.util.Scanner;

class Atoi
{
   /* ---
      Return 10^k in Binary 2's complement code
      --- */
   public static int Power(int k)
   {
      int r = 1;   // Stores: 00000000000000000000000000000001  in variable r

      for (int i = 0; i < k; i++ )
      {
         r = r * 10;  // The Java compiler will convert 10 into the 
		      // binary number 00000000000000000000000000001010
		      // This statement will multiply bin number r 
                      // with 00000000000000000000000000001010
      }

      return r;    // Returns a BINARY number in 2's compl 
		   // that represents the VALUE 10^k
   }
   


   /* ---
      parseInt(s): Ascii to Integer conversion function
      --- */
   public static int myParseInt(String s)
   {
      int[] digit = new int[20]; // Used to store individual digits in String s
      int  value, sign;
      int  i, pos;
      int  len;

      /* -------------------------
         Check for negative sign
         ------------------------- */
      if (s.charAt(0) == '-')
      {  sign = -1;
         pos = 1;     // Start processing at charAt(1)
      }
      else
      {  sign = 0;
         pos  = 0;    // Start processing at charAt(0)
      }

      /* -------------------------------------------
         Convert each character digit into 2s compl
	 (and keep a count on the number of digits
         ------------------------------------------- */
      len = 0;        // len counts # digits (without the leading '-')

      for ( i = pos; i < s.length(); i++ ) // Convert ASCII digits
      {
          digit[len] = s.charAt(i) - 48;
          len++;       // Count # digits in number
      }


      /* -----------------------------------------------------------
         ## DEBUG: Print the digits and its position in the number
         ----------------------------------------------------------- */
      System.out.println();
      System.out.println("       Digit   Position");
      System.out.println("=============================");
      for (int k = 0; k < len; k++)
      {
	 pos = (len - 1) - k;
         System.out.println("\t`" + digit[k] + "'    pos = " + pos);
      }
      System.out.println();
 
      /* ------------------------------------------
         Compute the absolute value of the number
         ------------------------------------------ */
      value = 0;
      for (int k = 0; k < len; k++)
      { 
         pos = (len - 1) - k;

         value = value + digit[k]*Power( pos );  // High school knowledge....
      }

      /* ========================================================
         Negate 2's complement representation if first character
	 of input was '-'
	 ========================================================= */
      if (sign == -1)
         value = -value;  // Compute the negative value (flip bits and add 1 !!)

      return(value);      // Return a BINARY 2's compl code 
   }

   public static void main(String[] args) 
   {
      Scanner in = new Scanner(System.in);

      String s1, s2;
      int i1, i2;

      System.out.print("Enter an integer (string) s1: ");
      s1 = in.next();
      System.out.println("We read the numeric string: \"" + s1 + "\"");

      i1 = myParseInt(s1);  // Same effect as: i1 = Integer.parseInt(s1); !!!!

      System.out.println("The integer VALUE for this numeric string is: " + i1);


      System.out.print("\nEnter another integer (string) s2: ");
      s2 = in.next();
      System.out.println("We read the numeric string: \"" + s2 + "\"");

      i2 = myParseInt(s2);  // Same effect as: i1 = Integer.parseInt(s1); !!!!

      System.out.println("The integer VALUE for this numeric string is: " + i2);

      System.out.println("===================================================");
      System.out.println("The sum of the integer values = " + (i1+i2) );
   }
}