function sum (id, pr, n, a):
    if id == 0:
        lo := 0
        hi := n

        cand := -1
        num := 0
        for i := lo until hi:
            if num == 0:
                cand := a[i]
            if cand == a[i]:
                num += 1
            else:
                num -= 1

        num := 0
        for i := lo until hi:
            if cand == a[i]:
                num += 1
            else:
                num -= 1

        if num > 0:
            print (cand)
        else:
            print (-1)