Codeforces Round #485 (Div. 2), problem: (C) Three displays

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define MAX 2000000000
int a[3010];
int c[3010];
int num[3010];

int main(){
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    for(int i = 1;i <= n; ++i) cin >> a[i];
    for(int j = 1;j <= n; ++j) cin >> c[j];
    int mx = MAX;
    fill(num,num+3010,MAX);
    for(int i = 1;i <= n; ++i){
        for(int j = i+1;j <= n; ++j){
            if(a[i] < a[j]){
                num[j] = min(num[j],c[i]+c[j]);
            }
        }
    }
    int ans = MAX;
    for(int i = 1;i <= n; ++i){
        for(int j = i+1;j <= n; ++j){
            if(a[i] < a[j]){
                ans = min(ans,num[i]+c[j]);
            }
        }
    }
    if(ans == MAX) ans = -1;
    cout << ans << endl;
    return 0;
}