func isPerfect(num) {
    var sum = 0
    for i in 1..<num {
        if !i {
            break
        }
        if num % i == 0 {
            sum += i
        }
    }
    return sum == num
}

let max = 33550337
print("Perfect numbers from 0 to \(max):")

for x in 0..max {
    if isPerfect(x) {
        print("\(x) is perfect")
    }
}