Submission

Score: 100

User: Nathlol2

Problemset: สามสหาย

Language: cpp

Time: 0.011 second

Submitted On: 2025-05-09 15:27:09

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ld long double
#define ar array
#define pii pair<int, int>
#define pll pair<ll, int>
#define fi first
#define sc second
#define INF (ll)1e18
#define MOD (ll)1000000007

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template <typename T>
using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define vt vector
#define pb push_back
#define eb emplace_back
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define sz(x) (int)(x).size()

#define F_OR(i, a, b, s) for (int i = (a); (s) > 0 ? i < (b) : i > (b); i += (s))
#define F_OR1(e) F_OR(i, 0, e, 1)
#define F_OR2(i, e) F_OR(i, 0, e, 1)
#define F_OR3(i, b, e) F_OR(i, b, e, 1)
#define F_OR4(i, b, e, s) F_OR(i, b, e, s)
#define GET5(a, b, c, d, e, ...) e
#define F_ORC(...) GET5(__VA_ARGS__, F_OR4, F_OR3, F_OR2, F_OR1)
#define rep(...) F_ORC(__VA_ARGS__)(__VA_ARGS__)
#define each(x, a) for (auto& x : a)

template <class T>
bool umin(T& a, const T& b) {
    return b < a ? a = b, 1 : 0;
}
template <class T>
bool umax(T& a, const T& b) {
    return a < b ? a = b, 1 : 0;
}

template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
void dbg_out() { cerr << endl; }
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cerr << ' ' << H; dbg_out(T...); }
#define dbg(...) cerr << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)

const int dx[4] = {0, 0, 1, -1}, dy[4] = {1, -1, 0, 0};
const int dxx[8] = {0, 0, 1, 1, 1, -1, -1, -1}, dyy[8] = {1, -1, 0, -1, 1, 0, -1, 1};
const int mxN = 5003;
void solve(){
    //sieve
    vt<bool> isp(mxN * 3, true);
    isp[0] = isp[1] = 0;
    rep(i, 2, mxN * 3){
        if(isp[i]){
            rep(j, i + i, mxN * 3, i){
                isp[j] = 0;
            }
        }
    }
    vt<int> p;
    rep(i, 2, mxN * 3){
        if(isp[i]){
            p.pb(i);
        }
    }
    ll ans = 0;
    int l, r;
    cin >> l >> r;
    each(x, p){
        if(x * 3 < l || r * 3 < x){
            continue;
        }
        rep(i, l, r + 1){
            if(i * 3 > x){
                continue;
            }
            ll need = x - i;
            ll a = (need / 2) - i + 1;
            ll b = r - ((need + 1) / 2) + 1;
            ans += max(min(a, b), 0LL);
        }
    }
    cout << ans << '\n';
}

int32_t main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int tc = 1;
    //cin >> tc;
    while(tc--){
        solve();
    }
}