from heapq import *
N,M,K = map(int,input().split())
A = []
for _ in range(N):
    a = list(map(int,input().split()))
    a.sort()
    A.append(a)
INF = 10**9
ans = 0

hq = [(-a,1) for a in A[0]]

while hq:
    i,j = heappop(hq)
    if j == N:
        ans = max(ans,-i)
        continue
    for a in A[j]:
        if -(i-a) > K:
            break
        heappush(hq,(i-a,j+1))
if ans == 0:
    print(-1)
else:
    print(K-ans)