from math import ceil
n,k=tuple(map(int,input().split()))
red=ceil((n*2)/k)
green=ceil((n*5)/k)
blue=ceil((n*8)/k)
print(red+green+blue)
462B - Appleman and Card Game | 1560C - Infinity Table |
1605C - Dominant Character | 1399A - Remove Smallest |
208A - Dubstep | 1581A - CQXYM Count Permutations |
337A - Puzzles | 495A - Digital Counter |
796A - Buying A House | 67A - Partial Teacher |
116A - Tram | 1472B - Fair Division |
1281C - Cut and Paste | 141A - Amusing Joke |
112A - Petya and Strings | 677A - Vanya and Fence |
1621A - Stable Arrangement of Rooks | 472A - Design Tutorial Learn from Math |
1368A - C+= | 450A - Jzzhu and Children |
546A - Soldier and Bananas | 32B - Borze |
1651B - Prove Him Wrong | 381A - Sereja and Dima |
41A - Translation | 1559A - Mocha and Math |
832A - Sasha and Sticks | 292B - Network Topology |
1339A - Filling Diamonds | 910A - The Way to Home |