def secti_do(n):
    soucet_vsech_cisel_do_n = 0
    for cislo in range(n+1):
        soucet_vsech_cisel_do_n += cislo
# soucet = soucet + cislo  je stejne jako: soucet += cislo

    return soucet_vsech_cisel_do_n

print(secti_do(10))