a,b,c,d,e=map(int,input().split())
n=(b-c)*a
p=0
ans=0
for i in range(1,n+1):
  if i==1:
    ans+=d
  else:
    if (i-1)%10==0 and e<=d:
      ans+=d-e
    else:
      ans+=d
print(ans)