func rep(s) {
    var x = s.Length() / 2
    while x > 0 {
        if s.StartsWith(s.Substring(x)) {
            return x
        }
        x -= 1
    }
    return 0
}

let m = [
    "1001110011",
    "1110111011",
    "0010010010",
    "1010101010",
    "1111111111",
    "0100101101",
    "0100100",
    "101",
    "11",
    "00",
    "1"
]

for s in m {
    if (rep(s) is n) && n > 0 {
        print("\(s)  \(n) rep-string \(s.Substring(n))")
    } else {
        print("\(s)  not a rep-string")
    }
}