n,m=map(int,input().split())
if n*m<=2*10**8:
    ans=0
    for i in range(1,n+1):
        cnt=0
        for j in range(1,m+1):
            cnt+=i%j
        ans=max(ans,cnt)
    print(ans)
else:
    ans=0
    for i in range(n,n-10000,-1):
        if i==0:
            break
        cnt=0
        for j in range(1,m+1):
            cnt+=i%j
        ans=max(ans,cnt)
    print(ans)