#ifndef Local
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#endif
#include <bits/stdc++.h>
#define int long long
#define pb push_back
#define lim 10000001
using namespace std;
const int mod=1000000007ll;
void solve(){
int a,b;
cin>>a>>b;
static signed all[lim];
memset(all,0,sizeof(all));
all[1]=0;
for(int i=2;i<lim;i++){
all[i]++;
for(int j=2*i;j<lim;j+=i){
all[j]+=i;
}
}
int ans=0;
for(int i=a;i<=b;i++){
//cerr<<abs(i-all[i])<<"\n";
ans+=abs(i-all[i]);
}
cout<<ans<<"\n";
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);cout.tie(NULL);
#ifdef Local
freopen("in.txt","r",stdin);
freopen("out.txt","w",stdout);
#endif
int t=1;
//cin>>t;
while (t--)
{
solve();
}
}
