m=gets.to_i
a=gets.split.map &:to_i
def d a,b
  if b==1
    a
  else
    a*d(a-1,b-1)
  end
end
if a==[0]
  p 1
else
t=m-a.inject(:+)-a.length+1
if t<0
  puts :NA
else
  p d(a.length+t,a.length)/d(a.length,a.length)%1000000007
end
end