gx,gy,N,F = map(int,input().split())
x = [0 for i in range(N)]
y = [0 for i in range(N)]
c = [0 for i in range(N)]
for i in range(N):
	x[i],y[i],c[i] = map(int,input().split())
INF = 10**9+7
dp = [[[INF,0] for j in range(100+1)]for i in range(100+1)]
dp[0][0] = [0,0]
for i in range(0,gx+1):
	for j in range(0,gy+1):
		if dp[i][j][0] == INF:
			continue
		for k in range(N):
			if i+x[k] <= 100 and j+y[k] <= 100 and (dp[i][j][1]>>k)&1 == 0 and dp[i+x[k]][j+y[k]][0] > dp[i][j][0]+c[k]:
				dp[i+x[k]][j+y[k]] = [dp[i][j][0]+c[k],dp[i][j][1]|(1<<k)]
		if i+1 <= 100 and dp[i+1][j][0] > dp[i][j][0]+F:
			dp[i+1][j] = [dp[i][j][0]+F,dp[i][j][1]]
		if j+1 <= 100 and dp[i][j+1][0] > dp[i][j][0]+F:
			dp[i][j+1] = [dp[i][j][0]+F,dp[i][j][1]]
print(dp[gx][gy][0])