Gx,Gy,N,F=map(int,input().split())

C=[list(map(int,input().split())) for i in range(N)]

DP=dict()
DP=[[1<<60]*(Gy+1) for i in range(Gx+1)]
DP[0][0]=0

for x,y,c in C:
    for i in range(Gx,-1,-1):
        for j in range(Gy,-1,-1):
            if DP[i][j]==1<<60:
                continue
            if i+x<Gx+1 and j+y<Gy+1:
                DP[i+x][j+y]=min(DP[i+x][j+y],DP[i][j]+c)

ANS=1<<60

for i in range(Gx+1):
    for j in range(Gy+1):
        ANS=min(ANS,DP[i][j]+(Gx-i)*F+(Gy-j)*F)

print(ANS)