n = io.read("*n") - 1
t = {}
t[1] = 1
for i = 1, n, 1 do
    local u = {}
    u[1] = 1
    sum = 1
    for j = 2, i, 1 do
        sum = sum + t[j]
        u[j] = sum
    end
    u[i + 1] = sum + t[i]
    t = u
end
io.write(t[n + 1])