local mod = 1000000007
local badd = function(a, b) return (a + b) % mod end
n = io.read("*n")
a = {}
for i = 1, n do
  a[i] = io.read("*n")
end
for i = n - 1, 1, -1 do
  for j = 1, i do
    a[j] = badd(a[j], a[j + 1])
  end
end
print(a[1])