import bisect

def main():
    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
    
    A.sort()
    
    low = 0
    high = p - 1
    ans = 0
    
    while low <= high:
        mid = (low + high) // 2
        total = 0
        for b in B:
            # Interval 1: [0, mid - b] if mid >= b
            cnt1 = 0
            if mid >= b:
                r1 = mid - b
                if r1 >= 0:
                    cnt1 = bisect.bisect_right(A, r1) - bisect.bisect_left(A, 0)
            
            # Interval 2: [P - b, mid + P - b] clamped to [0, P-1]
            l2 = p - b
            r2 = mid + p - b
            actual_l = max(l2, 0)
            actual_r = min(r2, p - 1)
            cnt2 = 0
            if actual_l <= actual_r:
                left = bisect.bisect_left(A, actual_l)
                right = bisect.bisect_right(A, actual_r)
                cnt2 = right - left
            
            total += cnt1 + cnt2
        
        if total >= k:
            ans = mid
            high = mid - 1
        else:
            low = mid + 1
    
    print(ans)

if __name__ == "__main__":
    main()