/* #pragma GCC optimize("Ofast,unroll-loops") */
#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
/* #define int long long */
const int mod = 1e7+7;
long long s[mod], b, a;
void sieve(){
s[1] = 1;
for(int i = 2; i <= 1e7; i++){
s[i]++;
for(int j = i * 2; j <= 1e7; j += i){
s[j] += i;
}
s[i] = abs(i - s[i]);
}
for(int i = 1; i <= 1e7; i++) s[i] += s[i-1];
}
void solve(){
cin >> a >> b;
cout << s[b] - s[a-1] << '\n';
debug(1000 * clock() / CLOCKS_PER_SEC);
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
sieve();
int test = 1;
/* cin >> test; */
for(int i = 1; i <= test; i++){
/* cout << "Case " << "#" << i << ": "; */
solve();
}
return 0;
}
