n, m, k = list(map(int, input().split()))
node = [[] for _ in range(n)]
A = [0] * n
B = [0] * n
for _ in range(m):
    u, v = list(map(lambda x: int(x)-1, input().split()))
    node[u].append(v)
    B[u] += 1
    A[v] += 1

if k+1 <= sum([1 for i in range(n) if B[i]]):
    ans = 0
    for i in range(n):
        if B[i]:
            ans += max(0, k-A[i])
else:
    ans = 0
    c = k+1
    C = [A[i] for i in range(n) if not B[i]]
    #print(C)
    C.sort(key = lambda x: -x)
    for i in range(n):
        if B[i]:
            c -= 1
            ans += max(0, k-A[i])
    for d in C[:c]:
        ans += max(0, k-d)
    
print(ans)