def f(n):
    fact=1
    if n != 0:
        for i in range(1,n+1):
            fact=fact*i
    return fact
        
def k_parmi_n(k,n):
    return f(n)/(f(k)*f(n-k))
    
def proba_binom(n,p,k):
    return k_parmi_n(k,n)*p**k*(1-p)**(n-k)
    
def seuil(n,p,alpha):
    proba=proba_binom(n,p,0)
    k=0
    while proba < 1-alpha:
        k=k+1
        proba=proba+proba_binom(n,p,k)
    return k
    
def seuil(n,p,alpha):
    proba=proba_binom(n,p,0)
    k=0
    while proba < ... :
        k=k+1
        proba=proba+proba_binom(...,...,...)
    return k