Submission

Score: 100

User: exoworldgd

Problemset: สามสหาย

Language: cpp

Time: 0.009 second

Submitted On: 2026-01-09 11:08:54

#pragma GCC optimize("O5,unroll-loops,inline,fast-math,omit-frame-pointer")
#pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt,tune=native,fma")
#include <bits/stdc++.h>
#define exoworldgd cin.tie(0)->sync_with_stdio(0), cout.tie(0)
#define int long long
using namespace std;
const int N=15005;
int a,b,dp[N],cnt[N],res;
bitset<N>ok;
signed main(void) {
    exoworldgd;
    cin>>a>>b,ok.set(),ok[0]=ok[1]=0;
    for(int i=2;i*i<N;i++)if(ok[i])for(int j=i*i;j<N;j+=i)ok[j]=0;
    for(int i=1;i<N;i++)cnt[i]=cnt[i-1]+ok[i];
    for(int i=a;i<=b;i++){
        for(int j=i;j<=b;j++){
            int s=i+j,lo=s+j,hi=min(N-1,s+b);
            if(lo<=hi)res+=cnt[hi]-cnt[lo-1];
        }
    }
    cout<<res;
}