N,M,K=map(int,raw_input().split())
graph = [[50000 for i in range(N)] for j in range(N)]
for i in range(M):
    u,v=map(int,raw_input().split())
    graph[u-1][v-1]=1
    graph[v-1][u-1]=1
for i in range(N):
    for j in range(N):
        for k in range(N):
            graph[j][k]=min(graph[j][k],graph[j][i]+graph[i][k])
points=[0]
for i in range(N-1,0,-1):
    if len(points) == K+1:
        break
    points.append(i)
    size=len(points)
    totalDist=[[50000 for i in range(size)] for j in range(1<<size)]
    totalDist[1][0]=0
    for m in range(1<<size):
        for s in range(size):
            if (m&(1<<s)) >0 and totalDist[m][s]!=50000:
                for t in range(size):
                    if(m&(1<<t)) == 0:
                        totalDist[m|(1<<t)][t]=min(totalDist[m|(1<<t)][t],totalDist[m][s]+graph[points[s]][points[t]])
    ok=False
    for end in range(size):
        if totalDist[(1<<size)-1][end]<=K:
            ok=True
            break
    if ok==False:
        points.pop()
ans=0
for p in points:
    #print p
    ans+=(1<<p)-1
print ans