Need assistance with conversion

Start
Repeat program
Enter digits into input box
scan the text string to find number of characters
if number of characters < 1 or > 3
store digits as variables integer = [a,b,c]
else if invalid number of characters entered
print invalid message "Character limit out of range"
(return previous step)
else if scan the variables (left first)
if (a,b,c >= 0 && < 8 ) then
pick of successive digit 
while not last digit
if digit =='0' concatenate "000" to right end of result 
if digit =='1' concatenate "001" to right end of result 
if digit =='2' concatenate "010" to right end of result 
if digit =='3' concatenate "011" to right end of result 
if digit =='4' concatenate "100" to right end of result 
if digit =='5' concatenate "101" to right end of result 
if digit =='6' concatenate "110" to right end of result 
if digit =='7' concatenate "111" to right end of result 
else if
characters out of range
print invalid message: "Characters entered out of range"
(return previous step)
end of string
print result into output box
end while 
calculate product of new result = c*8^0
end of string ? 
print new result into output box
else if proceed with next digit
calculate product of result = new result + b*8^1
end of string ? 
print result into output box
else if proceed with last digit
calculate product of result = result + a*8^2
print result into output box
end of string
print "Do you want another attempt?"
until answer != "yes" repeat program
else
End