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 for j in range(100+1)]for i in range(100+1)]
dp[0][0] = 0
for i in range(0,100+1):
	for j in range(0,100+1):
		if dp[i][j] == INF:
			continue
		for k in range(N):
			if i+x[k] <= 100 and j+y[k] <= 100:
				dp[i+x[k]][j+y[k]] = min(dp[i+x[k]][j+y[k]],dp[i][j]+c[k])
		if i+1 <= 100:
			dp[i+1][j] = min(dp[i+1][j],dp[i][j]+F)
		if j+1 <= 100:
			dp[i][j+1] = min(dp[i][j+1],dp[i][j]+F)
print(dp[gx][gy])