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import sys

def solve(input):
    def oracle_builder(invert):
        def oracle(a, b, i):
            if i == 0:
                return True
            else:
                odd = i % 2 == 0
                if invert:
                    odd = not odd
                return a < b if odd else a > b
        return oracle


    a = solve_case(input, oracle_builder(True))
    b = solve_case(input, oracle_builder(False))
    return min(a, b)    

def solve_case(input, oracle):
    MIN_V = int(-1e9)
    MAX_V = int(1e9)
    INF = int(1e6)
    last = {
        MIN_V: 1,
        input[0]: 0,
        MAX_V: 1
    }
    for i in range(1, len(input)):
        cur = {}
        for q in [MIN_V, input[i], MAX_V]:
            cost = 0 if q == input[i] else 1
            cur[q] = INF
            for p in [MIN_V, input[i-1], MAX_V]:
                if oracle(p, q, i):
                    cur[q] = min(cur[q], last[p] + cost)
        last = cur
    return min(last.values())


sys.stdin.readline()
input = [int(v) for v in sys.stdin.readline().strip().split()]
print(solve(input))