calculate the first 50 fibonacci number's sum

def sumFibonacci(size: Int): Long {
    var first = 0L
    var second = 1L
    var sum = 0L
    var count = 0
    while (count < size) {
        sum += second
        val temp = first + second
        first = second
        second = temp
        count += 1
    }
    return sum
}