#include <iostream>
#include <cmath>
using namespace std;
int main() {
int p[4000];
int pc = 0;
for (int i = 2; i < 4000; i++) {
bool f = true;
for (int j = 0; j < pc; j++) {
if (i % p[j] == 0) {
f = false;
break;
}
}
if (f) {
p[pc++] = i;
}
}
int a, b;
cin >> a >> b;
int f[b+1];
f[1] = 1;
for (int i = 2; i <= b; i++) {
int q = 0;
for (int j = 0; j < pc; j++) {
if (i % p[j] == 0) {
q = p[j];
break;
}
}
if (q) {
int t = q, s = 1;
while (i % t == 0) {
s += t;
t *= q;
}
t /= q;
f[i] = s * f[i/t];
} else {
f[i] = i - 1;
}
}
long long ans = 0;
for (int i = a; i <= b; i++) {
ans += abs(f[i] - i - i);
}
cout << ans << endl;
return 0;
}
