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]))
    B.sort()
    
    left = 0
    right = p - 1
    ans = p  # Initialize with a value larger than possible maximum
    
    while left <= right:
        mid = (left + right) // 2
        total = 0
        
        for a in A:
            # First part: B_j <= mid - a if mid >= a
            if mid >= a:
                s1 = mid - a
                c1 = bisect.bisect_right(B, s1)
            else:
                c1 = 0
            
            # Second part: B_j in [p - a, mid + (p - a)] mod p
            start = p - a
            end = mid + (p - a)
            end = min(end, p - 1)
            
            if start > end:
                c2 = 0
            else:
                # Find the count of B elements in [start, end]
                l = bisect.bisect_left(B, start)
                r = bisect.bisect_right(B, end)
                c2 = r - l
            
            total += c1 + c2
        
        if total >= k:
            ans = mid
            right = mid - 1
        else:
            left = mid + 1
    
    print(ans)

if __name__ == "__main__":
    main()