T,S,D = map(int, input().split())
ans = 0
while D>0:
    if 0<=T<6 or 18<=T<24:
        if D>=S:
            ans+=1
            D-=S
        else:
            ans+=D/S
            D-=S
    else:

        D-=S
    T=(T+1)%24
print(ans)