#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define st first
#define nd second
using namespace std;
typedef long long ll;
typedef __int128 lll;
const int mod = 1e9 + 7;
const int N = 1e6 + 5;
pair<ll, ll> s[N];

pair<ll, ll> operator+(pair<ll, ll> l, pair<ll, ll> r) {
  return {l.st + r.st, l.nd + r.nd};
}

lll solve(ll c, ll p) {
  auto above = [&](ll x, ll y) {
    return x <= (p - 1) / 2 && x * (lll)x + c < p * (lll)y;
  };
  auto deriv = [&](ll x, pair<ll, ll> r) {
    return 2 * x * r.nd >= r.st * p;
  };
  lll ans = 0;
  ll y = (1 + c) / p + 1, x = 1;
  pair<ll, ll> l = {1, 0}; // 1/0
  pair<ll, ll> r = {0, 1}; // 0/1
  int top = 0;
  s[0] = l; // 1/0
  while (x < (p - 1) / 2) {
    while (above(x + r.nd, y + r.st)) { // walk along convex hull
      ans += (y + y + r.st - 1) * (r.nd - 1) / 2 + y - 1;
      y += r.st;
      x += r.nd;
    }
    while (top >= 0 && !above(x + r.nd, y + r.st)) { // walk up the tree
      l = r;
      r = s[top--];
    }
    while (x + l.nd + r.nd <= (p - 1) / 2) { // walk down the tree
      auto d = l + r;
      // someone below dy/dx?
      if (above(x + d.nd, y + d.st)) {
        s[++top] = r;
        r = d;
      } else if (deriv(x + d.nd, r))
        break;
      else
        l = d;
    }
  }
  return ans + y - 1;
}

int main() {
  ios_base::sync_with_stdio(false); cin.tie(0);
  ll p, l, r; cin >> p >> l >> r;
  ll ans = solve(p - l, p) - solve(p - r - 1, p);
  cout << ans << "\n";
}