import strscans

let
  (_, a, b, c, d, e) = stdin.readAll.scanTuple"$i $i $i $i $i"
var
  pt, cal: int
  ans = a - b

for x in 0..c:
  pt = a + x * d
  cal = b + x * e
  ans = max(ans, pt - cal)

echo ans