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
    ans = high
    
    while low <= high:
        mid = (low + high) // 2
        total = 0
        for s in A:
            if mid >= s:
                x = mid - s
                cnt1 = bisect.bisect_right(B, x)
            else:
                cnt1 = 0
            
            lower = P - s
            upper = mid + P - s
            upper = min(upper, P - 1)
            
            if upper < lower:
                cnt2 = 0
            else:
                left = bisect.bisect_left(B, lower)
                right = bisect.bisect_right(B, upper)
                cnt2 = right - left
            
            total += cnt1 + cnt2
            if total > K:
                break
        
        if total >= K:
            ans = mid
            high = mid - 1
        else:
            low = mid + 1
    
    print(ans)

find_kth_smallest()