N, K, P = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))

def func(n):
    SUM = 0
    for i in range(N):
        if A[i] <= n:
            SUM += cum[n-A[i]+1]
        if 1 <= A[i]:
            SUM += cum[-1]-cum[P-A[i]]
            if n < A[i]-1:
                SUM -= cum[-1]-cum[(n-A[i])%P+1]
    return SUM

cum = [0]*(P+1)
for i in range(N):
    cum[B[i]+1] += 1
for i in range(2, P+1):
    cum[i] += cum[i-1]

left = -1
right = P-1
while left+1 < right:
    mid = (left+right)//2
    if func(mid) < K:
        left = mid
    else:
        right = mid

print(right)