gx,gy,n,f=map(int,input().split())
c=[list(map(int,input().split()))for _ in[0]*n]
gx+=1
gy+=1
d=[[1e99]*gx for _ in[0]*gy]
d[0][0]=0
def dp(x,y,u):
	for i in range(n):
		if u[i]:continue
		nx=x+c[i][0]
		ny=y+c[i][1]
		if nx<gx and ny<gy and d[y][x]+c[i][2]<d[ny][nx]:
			d[ny][nx]=d[y][x]+c[i][2]
			nu=u[:]
			nu[i]=True
			dp(nx,ny,nu)
	nx=x+1
	ny=y
	if nx<gx and ny<gy and d[y][x]+f<d[ny][nx]:
		d[ny][nx]=d[y][x]+f
		dp(nx,ny,u[:])
	nx=x
	ny=y+1
	if nx<gx and ny<gy and d[y][x]+f<d[ny][nx]:
		d[ny][nx]=d[y][x]+f
		dp(nx,ny,u[:])
dp(0,0,[False]*n)
print(d[-1][-1])