func swapCase(string: String) -> String {
    var swappedCaseString: String = ""
    for character in string {
        switch character {
        case "a"..."z":
            let uppercaseCharacter = (String(character)).uppercased()
            swappedCaseString += uppercaseCharacter
        case "A"..."Z":
            let lowercaseCharacter = (String(character)).lowercased()
            swappedCaseString += lowercaseCharacter
        default:
            fatalError()
        }
    }
    return swappedCaseString
}

let str = readLine()!
print(swapCase(string: str))