import strscans

let (_, a, b, c, d, e) = stdin.readAll.scanTuple"$i $i $i $i $i"

let n = a * (b - c)
var
  x = d
  ans = 0

for i in 1..n:
  if i mod 10 == 0:
    if x >= e:
      x.dec e
      ans.inc x
      continue
  
  ans.inc x

echo ans