func isValid(_ inpt:String) -> Bool {
    let num = Int(inpt)
    if(num == nil) {
        return false
    }
    if num! < 0 || num! > 12345 {
        return false
    }
    
    let str = String(num!)
    
    return inpt == str
}

var ans = "NG"
if(isValid(readLine()!) && isValid(readLine()!)) {
    ans = "OK"
}
print(ans)