from sys import stdin
input = stdin.readline

N, M, K = map(int, input().split())
G = [[] for _ in range(N)]
cnt = [[0]*2 for _ in range(N)]
for _ in range(M):
    u, v = map(int, input().split())
    u, v = u-1, v-1
    cnt[u][0] += 1
    cnt[v][1] += 1

cnt = [tuple(c) for c in cnt]
cnt.sort(reverse=True)
L, R = None, None
for i in range(N):
    if cnt[i][0] == 0:
        L = cnt[:i]
        R = cnt[i:]
        break
else:
    L = cnt[:]
    R = []

ans = 0
for a, b in L:
    ans += max(K-b, 0)
for i in range(max((K+1)-len(L), 0)):
    ans += max(K-R[i][1], 0)

print(ans)