sumU

#!/bin/bash
Num1=$1
Num2=$2
len1=0
len2=0
while [[ "${Num1:$len1:1}" != "" ]]; do
    let "len1=$len1+1"; 2>nul
done;
while [[ "${Num2:$len2:1}" != "" ]]; do
    let "len2=$len2+1"; 2>nul
done;
if [[ $len1 == $len2 ]]
then
    len=$len1
else
    if [[ $len1 > $len2 ]]
    then

        len=$len1
        while [[ $len2 != $len ]]; do
            Num2=0$Num2
            let "len2=$len2+1"
        done
    else
        len=$len2
        while [[ $len1 != $len ]]; do
            Num1=0$Num1
            let "len1=$len1+1"
        done
    fi
fi
rem=0
let "len=$len-1"
let "curn=${Num1:$len:1}+${Num2:$len:1}"
if [[ ${curn:1:1} == "" ]]
then
    ans=$curn
    rem=0
else
    ans=${curn:1:1}
    rem=1
fi
while [[ $len > 0 ]]; do
    let "len=$len-1"
    let "curn=${Num1:$len:1}+${Num2:$len:1}+$rem"
    if [[ ${curn:1:1} == "" ]]
    then
        ans=$curn$ans
        rem=0
    else
        ans=${curn:1:1}$ans
        rem=1
    fi
done
echo $ans