n = int(input())
A = list(map(int, input().split()))

INF = 10**18
DP = [[0 for _ in range(4)] for _ in range(n + 1)]
for i in range(n):
    a = A[i]
    for j in range(4):
        if DP[i][j] == -INF:
            continue
        DP[i + 1][0] = max(DP[i + 1][0], DP[i][j] + a)
        DP[i + 1][1] = max(DP[i + 1][1], DP[i][j] - a)
        DP[i + 1][2] = max(DP[i + 1][2], DP[i][j] * a)
        if a == 0:
            DP[i + 1][3] = -INF
        else:
            DP[i + 1][3] = max(DP[i + 1][3], DP[i][j] // a)
print(max(DP[n]))