import bisect

def find_kth_smallest():
    import sys
    input = sys.stdin.read
    data = input().split()
    idx = 0
    N = int(data[idx])
    idx += 1
    K = int(data[idx])
    idx += 1
    P = int(data[idx])
    idx += 1
    
    A = list(map(int, data[idx:idx+N]))
    idx += N
    B = list(map(int, data[idx:idx+N]))
    idx += N
    
    B.sort()
    
    low = 0
    high = P - 1
    answer = 0
    
    while low <= high:
        mid = (low + high) // 2
        total = 0
        for x in A:
            # Case 1: y <= mid - x
            target_case1 = mid - x
            if target_case1 >= 0:
                cnt1 = bisect.bisect_right(B, target_case1)
            else:
                cnt1 = 0
            
            # Case 2: y >= (P - x) and y <= min(mid + P - x, P-1)
            lower_case2 = P - x
            upper_case2 = mid + P - x
            if upper_case2 > P - 1:
                upper_case2 = P - 1
            
            if lower_case2 > upper_case2:
                cnt2 = 0
            else:
                left = bisect.bisect_left(B, lower_case2)
                right = bisect.bisect_right(B, upper_case2)
                cnt2 = right - left
            
            total += cnt1 + cnt2
        
        if total >= K:
            answer = mid
            high = mid - 1
        else:
            low = mid + 1
    
    print(answer)

find_kth_smallest()