h,w,n,f=map(int,input().split())
X=10**10
q=[[X]*(w+1) for i in range(h+1)]
q[0][0]=0
for _ in range(n):
  x,y,c=map(int,input().split())
  for i in reversed(range(h+1)):
    for j in reversed(range(w+1)):
      if i-x>=0 and j-y>=0:
        q[i][j]=min(q[i][j],q[i-x][j-y]+c)
a=X
for i in range(h+1):
  for j in range(w+1):
    a=min(a,q[i][j]+(h-i+w-j)*f)
print(a)