a, b = map(int,input().split())
sec = (a * 60 + b) * 60

aCalc = sec / 3600
bCalc = (sec % 3600) / 60

positionA = aCalc / 12 * 100
positionB = bCalc / 60 * 100



minimum = 9999
minimumS = -1
for i in range(3900):
    aCalc = (sec + i)  / 3600
    bCalc = ((sec + i) % 3600) / 60

    positionA = ( aCalc / 12 * 100 ) % 100
    positionB = ( bCalc / 60 * 100 ) % 100

    difference = abs(positionA - positionB)
    if minimum > difference:
        minimum = difference
        minimumS = i

'''
aCalc0 = (sec + minimumS)  / 3600
bCalc0 = ((sec + minimumS) % 3600) / 60
positionA0 = ( aCalc0 / 12 * 100 ) % 100
positionB0 = ( bCalc0 / 60 * 100 ) % 100

aCalc1 = (sec + minimumS + 1)  / 3600
bCalc1 = ((sec + minimumS + 1) % 3600) / 60
positionA1 = ( aCalc1 / 12 * 100 ) % 100
positionB1 = ( bCalc1 / 60 * 100 ) % 100

if (positionA0 - positionB0)*(positionA1 - positionB1) < 0:
    minimumS += 1
'''
print(minimumS)