N = int(input())
A = [int(a) for a in input().split()]
X = [A[i] - A[i+1] for i in range(0, 2 * N, 2)]
L = [0] * (N+1)
for i in range(N):
    L[i+1] = L[i] + X[i]
R = [0] * (N+1)
for i in range(N)[::-1]:
    R[i] = R[i+1] + X[i]

print(max([L[i] - R[i] for i in range(N+1)]))