IF = (N,p) ->
    [bI,bS] = [0,N]
    somme = 0
    until somme >= 0.025
        somme += binomiale(N,p,bI++)
    bI--
    somme = 0
    until somme >= 0.025
        somme += binomiale(N,p,bS--)
    bS++
    [bI,bS]