#region Header
#!/usr/bin/env python3
# from typing import *

import sys
import io
import math
import collections
import decimal
import itertools
from queue import PriorityQueue
import bisect
import heapq

def input():
    return sys.stdin.readline()[:-1]

sys.setrecursionlimit(1000000)
#endregion

# _INPUT = """3 3 2 1
# 1 2 2
# 2 1 2
# """
# sys.stdin = io.StringIO(_INPUT)


def main():
    Gx, Gy, N, F = map(int, input().split())
    crystals = []
    for _ in range(N):
        _x, _y, _c = map(int, input().split())
        crystals.append((_x, _y, _c))

    dp = [[[10**10 for _ in range(Gy+1)] for _ in range(Gx+1)] for _ in range(N+1)]
    dp[0][0][0] = 0
    for n in range(N):
        for x in range(Gx+1):
            for y in range(Gy+1):
                dp[n+1][x][y] = min(dp[n+1][x][y], dp[n][x][y])
                crystal = crystals[n]
                x1 = x + crystal[0]
                y1 = y + crystal[1]
                if x1 <= Gx and y1 <= Gy:
                    dp[n+1][x1][y1] = min(dp[n+1][x1][y1], dp[n][x][y] + crystal[2])

    cost_min = 10**10
    for x in range(Gx+1):
        for y in range(Gy+1):
            d = (Gx - x) + (Gy - y)
            cost = dp[N][x][y] + F * d
            cost_min = min(cost_min, cost)
    print(cost_min)


if __name__ == '__main__':
    main()