IDENTIFICATION DIVISION.
       PROGRAM-ID. day_03.
       AUTHOR. Trey Bastian.
       ENVIRONMENT DIVISION.
       INPUT-OUTPUT SECTION.
       FILE-CONTROL.
       SELECT input-file ASSIGN TO "./input.txt"
           ORGANIZATION IS LINE SEQUENTIAL.
       DATA DIVISION.
       FILE SECTION.
       FD input-file.
       01 input-line PIC Z(4096). 
       WORKING-STORAGE SECTION.
       01 idx PIC 9(4).
       01 idx-2 PIC 9(4).
       01 len PIC 9(4).

       01 maxim PIC 9 VALUE 0.
       01 digit PIC 9 VALUE 0.

       01 joltage PIC XX.
       01 result PIC 9(10) VALUE 0.

       
       01 eof PIC X.
           88 eof-y VALUE "Y".
           88 eof-n VALUE "N".

       PROCEDURE DIVISION.
         OPEN INPUT input-file.
         SET eof-n to TRUE.
         PERFORM UNTIL eof-y
             READ input-file AT END
                 SET eof-y to TRUE
             NOT AT END
                MOVE FUNCTION LENGTH(FUNCTION TRIM(input-line)) TO len
                MOVE 0 TO maxim
      *first pass leave something on the right
                PERFORM VARYING idx FROM 1 UNTIL idx > len - 1 
                    MOVE FUNCTION NUMVAL(input-line(idx:1)) TO digit
                    IF maxim < digit
                      MOVE digit TO maxim
                      MOVE idx TO idx-2
                    END-IF
                END-PERFORM 
      * need the next index 
                MOVE maxim TO joltage(1:1)
                MOVE 0 TO maxim
                ADD 1 TO idx-2 
                PERFORM VARYING idx-2 FROM idx-2  UNTIL idx-2 > len
                  MOVE FUNCTION NUMVAL(input-line(idx-2:1)) TO digit
                  IF maxim < digit
                    MOVE digit TO maxim
                  END-IF
                END-PERFORM
                MOVE maxim TO joltage(2:1)
                ADD FUNCTION NUMVAL(joltage) TO result
              END-READ
         END-PERFORM.
         CLOSE input-file.
         DISPLAY result.
       STOP-RUN.