def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    N = int(input[idx]); idx +=1
    M = int(input[idx]); idx +=1
    K = int(input[idx]); idx +=1
    L = int(input[idx]); idx +=1

    edges = []
    for _ in range(L):
        X = int(input[idx])-1; idx +=1  # 0-based
        Y = int(input[idx])-1; idx +=1
        Z = int(input[idx]); idx +=1
        edges.append((-Z, -(X + Y), X, Y))  # Sort by -Z (ascending Z), then by -(X+Y) (ascending X+Y)

    # Sort the edges in the required order:
    # First by Z descending, then by (X+Y) descending
    edges.sort()

    used_buyers = [False] * N
    used_items = [False] * M
    total = 0

    for e in edges:
        Z_neg, sum_neg, X, Y = e
        Z = -Z_neg
        if not used_buyers[X] and not used_items[Y]:
            used_buyers[X] = True
            used_items[Y] = True
            total += (1 << Z)

    print(total)

if __name__ == '__main__':
    main()