def verif_isbn(code):
        a = int(code[0])*10
        b = int(code[0])*9
        c = int(code[0])*8
        d = int(code[0])*7
        e = int(code[0])*6
        f = int(code[0])*5
        g = int(code[0])*4
        h = int(code[0])*3
        i = int(code[0])*2
        result = a+b+c+d+e+f+g+h+i
        reste = result%11
        return reste