let K = Int(readLine()!)!
let b = readLine()!
let c = b.split(separator: " ")
let A = Int(c[0])!
let B = Int(c[1])!

var i = A
while i % K != 0{
    if i % K == 0 {
        print("OK")
        break
    }
    
    i += 1
    if i == 1001 {
        break
    }
}