C++ :

#include <iostream>
#include <cstdio>

using namespace std;
typedef long long ll;

int main()
{
    ll n,m,ans1,ans2,len,now,L,R,t;
    while(~scanf("%lld %lld",&n,&m))
    {
        ans1 = ans2 = 0;
        t = 1;
        /*for(int i = 1; i <= n; i++)
            ans1 += m % i;*/
        if(n >= m)
            ans2 = (n - m) * m,n = m;
        /*for(int i = 1; i <= m; i++)
            cout<<i<<":"<<m % i<<endl;*/
        L = 0;
        now = m;
        while(true)
        {
            t++;
            R = m / t + 1;
            if(R > now) break;
            if(R > n)
            {
                now = m / t;
                L = m % now;
                continue;
            }
            len = now - R + 1;
            R = L + (len - 1) * (t - 1);
            if(now > n)
            {
                L = m % n;
                len = n - m / t;
            }
            ans2 += (R + L) * len / 2;
            now = m / t;
            if(!now) break;
            L = m % now;
        }
        for(int i = min(now,n); i >= 2; i--) //提前跳出来的数有可能大于n;
            ans2 += m % i;
        cout<<ans2<<endl;
    }
}