GX,GY,N,F = map(int,input().split())
DP = [[0] * (GX+1) for i in range(GY+1)]
for i in range(N):
    tx,ty,tc = map(int,input().split())
    for y in reversed(range(GY+1)):
        for x in  reversed(range(GX+1)):
            if DP[y][x]>0 and y+ty<=GY and x+tx<=GX:
                DP[y+ty][x+tx] = min(DP[y+ty][x+tx],DP[y][x]+tc)
                if DP[y+ty][x+tx]==0:
                    DP[y+ty][x+tx]=DP[y][x]+tc
    DP[ty][tx] = min(DP[ty][tx],tc)
    if DP[ty][tx]==0:
        DP[ty][tx] = tc
ans = (GX+GY)*F
for y in range(GY+1):
    for x in range(GX+1):
        if DP[y][x] > 0:
            ans = min(ans,((GY+GX-y-x))*F+DP[y][x])

print(ans)