http://codeforces.com/contest/768/problem/B

main.cc

#include <bits/stdc++.h>

using namespace std;

using ll = long long;

ll getAt(ll x, ll cl, ll cr, ll pos) {
    if (cl == cr && cl == pos) {
        return x;
    }

    ll mid = cl + (cr - cl)/2;
    if (mid == pos) {
        return x&1;
    }

    if (pos < mid) {
        return getAt(x/2, cl, mid - 1, pos);
    } else {
        return getAt(x/2, mid + 1, cr, pos);
    }
}

int main(int argc, char **argv) {
//    ios::sync_with_stdio(false);
    srand(time(0));

#ifndef ONLINE_JUDGE
    freopen("/home/acarus/input.txt", "r", stdin);
#endif

    ll n, l, r;
    scanf("%lld %lld %lld", &n, &l, &r);
    --l, --r;

    ll s = log(n)/log(2);
    ll ss = 1ll;
    for (int i = 0; i < s; ++i) {
        ss = ss * 2 + 1;
    }

    ll cl = 0, cr = ss - 1;
    ll ans = 0ll;
    for (ll i = l; i <= r; ++i) {
      ans += getAt(n, cl, cr, i);
    }
    printf("%lld\n", ans);
    return 0;
}