let strArray = readLine()!.map{$0} for (i,str) in strArray.enumerated(){ var code = String(str).unicodeScalars.first!.value var usa = Int(code) - (i+1) % 26 if usa < 65{ usa = usa + 26 } let chrStr = Character(UnicodeScalar(usa)!) print(chrStr,terminator:"") } print()