N = int(input())
A = [0]+list(map(int,input().split()))
def sgn(x):
    if x>0:
        return 1
    elif x<0:
        return -1
    else:
        return 0
dp = [[0,0] for _ in range(N+1)]
dp[1] = [A[1],A[1]]
for i in range(2,N+1):
    a = A[i]
    if a!=0:
        dp[i][0] = max(dp[i-1][0]+a,dp[i-1][0]-a,dp[i-1][0]*a,abs(dp[i-1][0])//abs(a)*sgn(dp[i-1][0])*sgn(a),dp[i-1][1]+a,dp[i-1][1]-a,dp[i-1][1]*a,abs(dp[i-1][1])//abs(a)*sgn(dp[i-1][1])*sgn(a))
        dp[i][1] = min(dp[i-1][0]+a,dp[i-1][0]-a,dp[i-1][0]*a,abs(dp[i-1][0])//abs(a)*sgn(dp[i-1][0])*sgn(a),dp[i-1][1]+a,dp[i-1][1]-a,dp[i-1][1]*a,abs(dp[i-1][1])//abs(a)*sgn(dp[i-1][1])*sgn(a))
    else:
        dp[i][0] = max(dp[i-1][0],0,dp[i-1][1])
        dp[i][1] = min(dp[i-1][0],0,dp[i-1][1])
print(dp[N][0])