2021/04/22
import sys
N, d, k, c = map(int, sys.stdin.readline().split())
belt = []
sushi = dict()
for _ in range(N):
a = int(sys.stdin.readline())
belt.append(a)
for i in range(N):
belt.append(belt[i])
left = 0
right = k - 2
for i in range(right + 1):
if (belt[i] in sushi):
sushi[belt[i]] += 1
else:
sushi[belt[i]] = 1
ans = 0
while (right < 2 * N - 1):
right += 1
if (belt[right] in sushi):
sushi[belt[right]] += 1
else:
sushi[belt[right]] = 1
if (len(sushi) >= ans):
if (c in sushi):
ans = len(sushi)
else:
ans = len(sushi) + 1
sushi[belt[left]] -= 1
if (not sushi[belt[left]]):
del sushi[belt[left]]
left += 1
print(ans)