Solution to the problem 'Electronics Shop' (HackerRank)

Hi all! Here's my solution to the problem 'Electronics Shop' from HackerRank.

Question link: https://www.hackerrank.com/challenges/electronics-shop/problem

#include <bits/stdc++.h>

#define int long long

#define pb push_back

#define fi first

#define se second

#define pii pair<int,int>

using namespace std;

int32_t main()

{

    ios_base::sync_with_stdio(false);

    cin.tie(NULL);

    cout.tie(NULL);

    int b,n,m;

    cin>>b>>n>>m;

    vector<int> keyboard,usb;

    for(int i=0;i<n;i++){

        int x;

        cin>>x;

        keyboard.pb(x);

    }

    for(int i=0;i<m;i++){

        int x;

        cin>>x;

        usb.pb(x);

    }

    sort(keyboard.begin(),keyboard.end());

    sort(usb.begin(),usb.end());

    int ans=0,flg=0;

    if(keyboard[0]+usb[0]>b) cout<<-1;

    else{

        for(int i=n-1;i>=0;i--){

            for(int j=m-1;j>=0;j--){

                if(keyboard[i]+usb[j]<=b){

                    ans=max(ans,(keyboard[i]+usb[j]));

                }

            }

        }

        cout<<ans;

    }

    return 0;

}