def combi(n, r)
    q = 1
    1.upto(r){|k|q=q*(n-k+1)/k}
    return q
end

def solve(n)
    return Rational(combi(n,5),combi(99,5)).to_f*12
end

while cin = gets
    n = cin.to_i
    p solve(n)
end