USING: io kernel math math.parser sequences ;
readln string>number
[ drop 3 * ] reduce
number>string print
VVNJTkc6IGlvIGtlcm5lbCBtYXRoIG1hdGgucGFyc2VyIHNlcXVlbmNlcyA7CgogICByZWFkbG4gc3RyaW5nPm51bWJlcgogICBbIGRyb3AgMyAqIF0gcmVkdWNlCiAgIG51bWJlcj5zdHJpbmcgcHJpbnQ=