#include <cstdlib>
#include <iostream>
const int MM = 1e7 + 10;
int tab[MM]{};
void fill_tab() {
for (int i = 2; i < MM; i++) tab[i] = 1;
for (int i = 1; i * i <= MM; i++) {
for (int j = i * 2; j < MM; j += i) {
tab[j] += i;
}
}
}
int calculate_imperfection(const int &n) {
return std::abs(n - tab[n]);
}
int main() {
std::ios_base::sync_with_stdio(0);
fill_tab();
int a, b;
std::cin >> a >> b;
unsigned long long sum = 0;
for (int i = a; i <= b; i++) {
sum += calculate_imperfection(i);
}
std::cout << sum << std::endl;
return 0;
}
