'''li=[2,4,6,8,10,1,3,5,7,9]
n=int(input('1~10:'))

for i in range(len(li)):
    if li[i]==n:
        print(i)
        break'''



li=[2,4,6,8,10,12,14,16,18]
n=int(input('2,4,6,8,10,12,14,16,18: '))

s_index=0
e_index=len(li)-1

while s_index<=e_index:
    m_index=(s_index+e_index)//2
    print(s_index,e_index,m_index)
    if n<li[m_index]:
        e_index=m_index-1
    elif n>li[m_index]:
        s_index=m_index+1
    else:
        print(m_index)
        break

a9aff4da71772c87341f8c7273fd9c25514368bf
<mask token>

<mask token>
while s_index <= e_index:
    m_index = (s_index + e_index) // 2
    print(s_index, e_index, m_index)
    if n < li[m_index]:
        e_index = m_index - 1
    elif n > li[m_index]:
        s_index = m_index + 1
    else:
        print(m_index)
        break

<mask token>
li = [2, 4, 6, 8, 10, 12, 14, 16, 18]
n = int(input('2,4,6,8,10,12,14,16,18: '))
s_index = 0
e_index = len(li) - 1
while s_index <= e_index:
    m_index = (s_index + e_index) // 2
    print(s_index, e_index, m_index)
    if n < li[m_index]:
        e_index = m_index - 1
    elif n > li[m_index]:
        s_index = m_index + 1
    else:
        print(m_index)
        break

'''li=[2,4,6,8,10,1,3,5,7,9]
n=int(input('1~10:'))

for i in range(len(li)):
    if li[i]==n:
        print(i)
        break'''



li=[2,4,6,8,10,12,14,16,18]
n=int(input('2,4,6,8,10,12,14,16,18: '))

s_index=0
e_index=len(li)-1

while s_index<=e_index:
    m_index=(s_index+e_index)//2
    print(s_index,e_index,m_index)
    if n<li[m_index]:
        e_index=m_index-1
    elif n>li[m_index]:
        s_index=m_index+1
    else:
        print(m_index)
        break
