bzoj 1257

 1 #include<bits/stdc++.h>
 2 #define inc(i,l,r) for(int i=l;i<=r;i++)
 3 #define dec(i,l,r) for(int i=l;i>=r;i--)
 4 #define link(x) for(edge *j=h[x];j;j=j->next)
 5 #define mem(a) memset(a,0,sizeof(a))
 6 #define inf 1e9
 7 #define ll long long
 8 #define succ(x) (1<<x)
 9 using namespace std;
10 ll read(){
11     ll x=0,f=1;char ch=getchar();
12     while(!isdigit(ch)){if(ch==‘-‘)f=-1;ch=getchar();}
13     while(isdigit(ch))x=x*10+ch-‘0‘,ch=getchar();
14     return x*f;
15 }
16 ll n,k,t,ans;
17 int main(){
18     freopen("data.in","r",stdin);
19     n=read();k=read();
20     if(k<n){
21         ans=(ll)k*(n-k);n=k;
22     }
23     for(int i=1;i<=n;i=t+1){
24         t=k/i;t=k/t;
25         if(t>n)t=n;
26         ans+=(ll)k*(t-i+1)-(k/i)*(t-i+1)*(i+t)/2;
27     }
28     printf("%lld",ans);
29     return 0;
30 }