local n = io.read("*n", "*l")
local s = {}
for i = 1, n do
  s[i] = io.read()
end
local c = 0
local t = {}
for i = 1, n do
  for j = 1, n do
    if i ~= j then
      local z = s[i] .. s[j]
      if not t[z] then t[z] = true c = c + 1 end
    end
  end
end
print(c)