#include <bits/stdc++.h>
#define ll long long
#define fr first
#define sc second
#define mp make_pair
#define pb push_back
#define LEFT(a) ((a)<<1)
#define RIGHT(a) (LEFT(a) + 1)
#define MID(a,b) ((a+b)>>1)
using namespace std;
const int MOD=1e9+7,N=1e7;
const ll INF=1e18;
int A,B;
int prime[N+5];
ll f[N+5];
ll x,y,z,t;
ll ans;
int main(){
for (int i=2;i*i<=N;i++)
if (prime[i]==0)
for (int j=i*i;j<=N;j+=i)
if (prime[j]==0)
prime[j]=i;
cin>>A>>B;
f[1]=1;
for (int i=2;i<=B;i++){
if (prime[i]==0){
f[i]=i+1;
continue;
}
x=i;
y=0;
z=1;
t=1;
while (x%prime[i]==0){
t*=prime[i];
z+=t;
y++;
x/=prime[i];
}
f[i]=f[x]*z;
}
for (int i=A;i<=B;i++)ans+=abs(f[i]-2*i);
cout<<ans<<endl;
return 0;
}
