题目链接

题面：

题解：

代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<queue>
#include<vector>
#include<set>
#define ll long long
#define llu unsigned ll
#define ld long double
#define iu unsigned int
using namespace std;
const int inf=0x3f3f3f3f;
const ll lnf=0x3f3f3f3f3f3f3f3f;
const double dnf=1e15;
const double eps=1e-8;
const int maxn=10100;
ll ans,n,k;
int main(void)
{
    scanf("%lld%lld",&n,&k);
    ans=n*k;
    for(ll l=1,r;l<=min(n,k);l=r+1)
    {
        r=min(k/(k/l),n);
        ans-=(l+r)*(r-l+1)/2*(k/l);
    }
    printf("%lld\n",ans);
    return 0;
}