Caesar's cipher decryption

ciphr$="ňŭğŢűŸůųŮŦűŠůŧŸīğŠğłŠŤŲŠűğŢŨůŧŤűīğŠūŲŮğŪŭŮŶŭğŠŲğŠğłŠŤŲŠűĦŲğŢŨůŧŤűīğųŧŤğŲŧŨťųğŢŨůŧŤűīğłŠŤŲŠűĦŲğŢŮţŤğŮűğłŠŤŲŠűğŲŧŨťųīğŨŲğŮŭŤğŮťğųŧŤğŲŨŬůūŤŲųğŠŭţğŬŮŲųğŶŨţŤūŸğŪŭŮŶŭğŤŭŢűŸůųŨŮŭğųŤŢŧŭŨŰŴŤŲħŖŨŪŨůŤţŨŠĨ"

text$=""

shift=255

for n = 1 to length(ciphr$)

letter$= mid(ciphr$, n, 1)

m = asc(letter$)

text$=text$+chr(m-shift)

next n

print text$