gx,gy,N,F = map(int,input().split())
lsxyz = [list(map(int,input().split())) for i in range(N)]
inf = float('INF')
dp = [[inf]*(gy+1) for i in range(gx+1)]
dp[0][0] = 0


for i in range(N):
    x,y,z = lsxyz[i]
    dp2 = [[inf]*(gy+1) for i in range(gx+1)]
    for j in range(gx+1):
        for k in range(gy+1):
            if 0 <=j-x and 0 <=k-y:
                dp2[j][k] = min(dp[j][k],dp[j-x][k-y]+z)
            else:
                dp2[j][k] = dp[j][k]
    dp = dp2

for i in range(gx+1):
    for j in range(gy+1):
        if 0<=i-1:
            dp[i][j] = min(dp[i-1][j]+F,dp[i][j])
        if 0<=j-1:
            dp[i][j] = min(dp[i][j-1]+F,dp[i][j])
print(dp[-1][-1])