bzoj 1257

     商最多有sqrt（n）个。

     

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define int long long
using namespace std;
int n,k;
signed main()
{
    scanf("%lld%lld",&n,&k);
    int ans=n*k;if(n>k)n=k;
    int l,r,j;
    for(int i=1;i<=n;i=r+1)
    {
        int y=k/i;r=k/y;
        if(r>n)r=n;
        ans-=y*(r-i+1)*(i+r)/2;
    }
    printf("%lld\n",ans);
    return 0;
}