from itertools import *
from bisect import *
#from math import *
from collections import *
from heapq import *
from random import *
from decimal import *
import numpy as np
import sys

sys.setrecursionlimit(10 ** 6)
int1 = lambda x: int(x) - 1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
def MF(): return map(float, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LF(): return list(map(float, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
dij = [(1, 0), (0, 1), (-1, 0), (0, -1)]

def main():
    inf=10**9
    gx,gy,n,f=MI()
    xyc=[LI() for _ in range(n)]
    dp=[[inf]*(gy+1) for _ in range(gx+1)]
#    for i in range(gx+1):
#        dpi=dp[i]
#        for j in range(gy+1):
#            dpi[j]=f*(i+j)
    dp[0][0]=0
    for x,y,c in xyc:
        for i in range(gx+1):
            ni=i+x
            if ni>gx:break
            dpi=dp[i]
            dpni=dp[ni]
            for j in range(gy+1):
                nj=j+y
                if nj>gy:break
                pre=dpi[j]
                if pre==inf:continue
                if pre+c<dpni[nj]:dpni[nj]=pre+c
    ans=inf
    for i in range(gx+1):
        dpi=dp[i]
        for j in range(gy+1):
            val=dpi[j]+(gx-i+gy-j)*f
            if val<ans:ans=val
    print(ans)

main()