Gx,Gy,N,F=map(int,input().split())

C=[list(map(int,input().split())) for i in range(N)]


DP=[[1<<60]*(Gy+1) for i in range(Gx+1)]
DP[0][0]=0

for i in range(Gx+1):
    for j in range(Gy+1):
        if i+1<Gx+1:
            DP[i+1][j]=min(DP[i+1][j],DP[i][j]+F)

        if j+1<Gy+1:
            DP[i][j+1]=min(DP[i][j+1],DP[i][j]+F)

        for x,y,c in C:
            if i+x<Gx+1 and j+y<Gy+1:
                DP[i+x][j+y]=min(DP[i+x][j+y],DP[i][j]+c)

print(DP[Gx][Gy])