Spot the error

This Swift code contains one error – can you select the line that is incorrect?

Tip: You should mentally run the code from top to bottom, meaning that if line 3 says an integer should be returned and line 10 tries to return a string, line 10 is the wrong one.

func formatError(input; Int) -> String {

    var output: String = "ERROR \(input)"

    output += "\nPlease try again\n"

    return output

print(formatError(input: 24))