import sys

def solve():
    N = int(input())
    x = [int(i) for i in input().split()]

    xd2 = [xi // 2 for xi in x]

    pfx = [0] * (N + 1)
    for i in range(N):
        pfx[i + 1] = pfx[i] + xd2[i]

    ans = 0

    for i in range(N):
        ans = max(ans, pfx[i] + x[i] + pfx[N] - pfx[i + 1])

    print(ans)

if __name__ == '__main__':
    solve()