perfectornot.cpp

#include<iostream>
#include<cstdlib>
#include<vector>

#define long long long
#define nln '\n'

using namespace std;

int main()
{
    cin.tie(0)->sync_with_stdio(0);
    cout.tie(0)->sync_with_stdio(0);
    //freopen("perfectornot.inp", "r", stdin);
    long a, b;
    cin >> a >> b;

    vector<long> s(b+1, 1);
    s[1] = 0;
    for (long i = 2; i <= b; ++i)
        for (long j = 2*i; j <= b; j += i)
            s[j] += i;

    long ans = 0;
    for (long i = a; i <= b; ++i)
        ans += abs(i-s[i]);
    cout << ans << nln;

    return 0;
}