from copy import deepcopy

Gx, Gy, N, F = map( int, input().split() )
X = []
Y = []
C = []
for i in range( N ):
  x, y, c = map( int, input().split() )
  X.append( x )
  Y.append( y )
  C.append( c )

INF = int( 1e15 )

dp = [ INF for i in range( Gy + 1 ) ]
dp = [ deepcopy( dp ) for i in range( Gx + 1 ) ]
dp = [ deepcopy( dp ) for i in range( N + 1 ) ]
dp[ 0 ][ 0 ][ 0 ] = 0
for i in range( N ):
  for j in range( Gx + 1 ):
    for k in range( Gy + 1 ):
      if j + X[ i ] <= Gx and k + Y[ i ] <= Gy:
        dp[ i + 1 ][ j + X[ i ] ][ k + Y[ i ] ] = min( dp[ i + 1 ][ j + X[ i ] ][ k + Y[ i ] ], dp[ i ][ j ][ k ] + C[ i ] )
      if j + 1 <= Gx:
        dp[ i ][ j + 1 ][ k ] = min( dp[ i ][ j + 1 ][ k ], dp[ i ][ j ][ k ] + F )
        dp[ i + 1 ][ j + 1 ][ k ] = min( dp[ i + 1 ][ j + 1 ][ k ], dp[ i ][ j ][ k ] + F )
      if k + 1 <= Gy:
        dp[ i ][ j ][ k + 1 ] = min( dp[ i ][ j ][ k + 1 ], dp[ i ][ j ][ k ] + F )
        dp[ i + 1 ][ j ][ k + 1 ] = min( dp[ i + 1 ][ j ][ k + 1 ], dp[ i ][ j ][ k ] + F )
print( dp[ N ][ Gx ][ Gy ] )