class mf_graph:
    def __init__(self, N) :
        self.size = N
        self.g = [[] for i in range(self.size)]
        self.gsz = [0 for i in range(self.size)]

    def add_edge(self, u, v) :
        self.g[u].append([v, self.gsz[v], 1])
        self.g[v].append([u, self.gsz[u], 0])
        self.gsz[u] += 1
        self.gsz[v] += 1

    def Bfs(self, s, t) :
        q = [s]
        idx = 0
        q_sz = 1
        self.went[s] = t
        self.Iter[s] = self.dep[s] = 0
        while idx < q_sz :
            now = q[idx]
            idx += 1
            for i in self.g[now] :
                if i[2] > 0 and self.went[i[0]] != t :
                    self.went[i[0]] = t
                    self.dep[i[0]] = self.dep[now] + 1
                    self.Iter[i[0]] = 0
                    q_sz += 1
                    q.append(i[0])

    def Dfs(self, u, t, nv) :
        if u == t :
            return nv
        while self.Iter[u] < self.gsz[u] :
            i = self.Iter[u]
            if self.g[u][i][2] > 0 and self.dep[self.g[u][i][0]] > self.dep[u] :
                if self.Dfs(self.g[u][i][0], t, nv) > 0 :
                    self.g[u][i][2] = 0
                    self.g[self.g[u][i][0]][self.g[u][i][1]][2] = 1
                    return 1
            self.Iter[u] += 1
        return 0

    def flow(self, s, t) :
        self.dep = [0 for i in range(self.size)]
        self.went = [0 for i in range(self.size)]
        self.Iter = [0 for i in range(self.size)]
        cnt = 0; ans = 0; kInf = 1 << 30
        while True :
            cnt += 1
            self.Bfs(s, cnt)
            if self.went[s] != self.went[t] :
                break
            f = 0
            while True :
                f = self.Dfs(s, t, kInf)
                if f > 0 :
                    ans += f
                else :
                    break
        return ans

n, m, k, l = map(int, input().split())
x = [0] * l; y = [0] * l; z = [0] * l
for i in range(l) :
    x[i], y[i], z[i] = map(int, input().split())

edges = [[] for i in range(k + 1)]
for i in range(l) :
    edges[z[i]].append(i)

alivex = [True for i in range(n + 1)]
alivey = [True for i in range(m + 1)]

S = 0; T = n + m + 1
G = mf_graph(n + m + 2)
for j in range(1, n + 1) :
    G.add_edge(S, j)
for j in range(1, m + 1) :
    G.add_edge(j + n, T)

previous_edges = []
qu = []
qu_sz = 0
ans = 0

for i in range(k, -1, -1) :
    for j in edges[i] :
        if alivex[x[j]] and alivey[y[j]] : 
            previous_edges.append(j)
            G.add_edge(x[j], y[j] + n)

    gx = [[] for j in range(n + 1)]
    gy = [[] for j in range(m + 1)]

    for j in previous_edges :
        gx[x[j]].append(y[j])
        gy[y[j]].append(x[j])

    ans += G.flow(S, T) << i

    wentx = [False for i in range(n + 1)]
    wenty = [False for i in range(m + 1)]
    matchx = [-1 for i in range(n + 1)]
    matchy = [-1 for i in range(m + 1)]
    
    for j in range(1, n + 1) :
        for e in G.g[j] :
            if e[0] != S and e[2] == 0 and G.g[e[0]][e[1]][2] == 1 :
                matchx[j] = e[0] - n
                matchy[e[0] - n] = j

    for j in range(1, n + 1) :
        if matchx[j] < 0 :
            wentx[j] = True
            qu_sz += 1
            qu.append(j)
    
    while qu_sz > 0 :
        idx = qu.pop()
        qu_sz -= 1
        for j in gx[idx] :
            if not wentx[matchy[j]] :
                wentx[matchy[j]] = True
                qu_sz += 1
                qu.append(matchy[j])

    for j in range(1, n + 1) :
        if not wentx[j] :
            alivex[j] = False

    for j in range(1, m + 1) :
        if matchy[j] < 0 :
            wenty[j] = True
            qu_sz += 1
            qu.append(j)

    while qu_sz > 0 :
        idx = qu.pop()
        qu_sz -= 1
        for j in gy[idx] :
            if not wenty[matchx[j]] :
                wenty[matchx[j]] = True
                qu_sz += 1
                qu.append(matchx[j])

    for j in range(1, m + 1) :
        if not wenty[j] :
            alivey[j] = False

    for j in range(1, n + 1) :
        if not wentx[j] :
            for idx in range(G.gsz[j]) :
                e = G.g[j][idx]
                if e[2] >= 0 and e[0] != S and not wenty[e[0] - n] and matchx[j] != e[0] - n :
                    G.g[j][idx][2] = 0
                    G.g[e[0]][e[1]][2] = 0

    psz = len(previous_edges)
    j = 0
    while j < psz :
        idx = previous_edges[j]
        if not wentx[x[idx]] and not wenty[y[idx]] and matchx[x[idx]] != y[idx] :
            psz -= 1
            previous_edges[j], previous_edges[psz] = previous_edges[psz], previous_edges[j]
            previous_edges.pop()
            j -= 1
        j += 1
print(ans)