n = int(input())
l = [*map(int, input().split())]
l_0 = l_1 = r_0 = r_1 = 0
for i in range(0, n):
if l[i] == 0:
l_0 = i
break
for i in range(0, n):
if l[i] == 1:
l_1 = i
break
for i in range(n - 1, -1, -1):
if l[i] == 0:
r_0 = i
break
for i in range(n - 1, -1, -1):
if l[i] == 1:
r_1 = i
break
print(max([abs(l_0 - r_1), abs(l_0 - l_1), abs(r_0 - l_1), abs(r_0 - r_1)]))