INF = 10 ** 10

gx, gy, n, f = map(int,input().split(' '))
x = [0] * n
y = [0] * n
c = [0] * n
for i in range(n):
    x[i], y[i], c[i] = map(int,input().split(' '))

dp = [[INF] * (gx+1) for i in range(gy+1)]

dp[0][0] = 0
for k in range(n):
    for i in range(gy+1)[::-1]:
        for j in range(gx+1)[::-1]:
            if i+y[k] <= gy and j+x[k] <= gx:
                dp[i+y[k]][j+x[k]] = min(dp[i+y[k]][j+x[k]],dp[i][j]+c[k])

ans = f * (gx + gy)
for k in range(n):
    for i in range(gy+1):
        for j in range(gx+1):
            ans = min(ans,dp[i][j]+f*(gy-i+gx-j))

print(ans)