Mysterious Function

Chris received the following algorithm written in Python :

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def mysterious(L,i,j):
    if i + 1 == j:
        return -INF

    mid = (i + j) / 2

    x = max(L[i:mid])
    y = max(L[mid:j])
    if x == y:
        return x

    if x > y:
        return max(mysterious(L,i,mid),y)
    else:
        return max(mysterious(L,mid,j),x)

It takes in an integer list $L$ and initially $i=0$ and $j=\text{len}(L) > 1$ . What does this algorithm returns?

Details and Assumptions

• Assume that INF is larger than any integer in $L$ .