def test_case1(): assert solution([3, 4, 3, 2, 3, -1, 3, 3]) == 0
def test_case6(): assert solution([1, 3, 3]) == 1
def test_case5(): assert solution([3, 3]) == 0
def test_case4(): assert solution([3, 2]) == -1
def test_case3(): assert solution([]) == -1
def test_case2(): assert solution([3]) == 0