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

    def add_edge(self, u, v, c) :
        self.g[u].append((v, len(self.g[v]), c))
        self.g[v].append((u, len(self.g[u]) - 1, 0))

    def Bfs(self, s, t) :
        q = []
        self.went[s] = t
        self.Iter[s] = self.dep[s] = 0
        q.append(s)
        while len(q) :
            now = q.pop()
            for i in self.g[now] :
                if i[2] 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.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] :
                tmp = self.Dfs(self.g[u][i][0], t, min(self.g[u][i][2], nv))
                if tmp > 0 :
                    self.g[u][i] = (self.g[u][i][0], self.g[u][i][1], self.g[u][i][2] - tmp)
                    self.g[self.g[u][i][0]][self.g[u][i][1]] = (self.g[self.g[u][i][0]][self.g[u][i][1]][0], self.g[self.g[u][i][0]][self.g[u][i][1]][1], self.g[self.g[u][i][0]][self.g[u][i][1]][2] + tmp) 
                    return tmp
            self.Iter[u] += 1
        return 0

    def flow(self, s, t) :
        for i in range(self.size) :
            self.gsz[i] = len(self.g[i])
        cnt = self.went[s]
        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] * (n + 1)
alivey = [True] * (m + 1)
wentx = [False] * (n + 1)
wenty = [False] * (m + 1)
val = [0] * (k + 1)
matchx = [0] * (n + 1)
matchy = [0] * (m + 1)

S = 0; T = n + m + 1

previous_edges = []
lst = 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)

    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])

    G = mf_graph(n + m + 2)
    for j in range(1, n + 1) :
        G.add_edge(S, j, 1)
    for j in range(1, m + 1) :
        G.add_edge(j + n, T, 1)
    for j in previous_edges :
        G.add_edge(x[j], y[j] + n, 1)

    val[i] = G.flow(S, T) - lst
    lst += val[i]

    for j in range(1, n + 1) :
        matchx[j] = -1
    for j in range(1, m + 1) :
        matchy[j] = -1

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

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

    while len(qu) :
        idx = qu.pop()
        for j in gy[idx] :
            if not wenty[matchx[j]] :
                wenty[matchx[j]] = True
                qu.append(matchx[j])

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

    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

    del G
    del gx
    del gy

ans = 0
for i in range(0, k + 1) :
    ans += val[i] << i
print(ans)