subcadeias.cpp

#include<bits/stdc++.h>
#define int long long
#define ms(v) memset(v, -1, sizeof v)
#define pb push_back
#define mp make_pair
#define ll long long int
#define pi pair <int,int>
#define itn int
#define fr first
#define sc second
#define srt(v) sort(v.begin(), v.end())
#define rvs(v) reverse(v.begin(), v.end())
#define mod 1000000007
#define N 510

using namespace std;

int n;
char v[N];

main(){
    ios::sync_with_stdio(false); cin.tie(0);
    
    cin >> n;

    for(int i = 0;i < n;i++) cin >> v[i];

    int res = 0;

    //palindromos de tamanho impar

    for(int i = 0;i < n;i++){
        int aux = 1;
        int sz = 1;

        for(int j = i-1;j >= 0;j--){
            if(v[i-sz] != v[i+sz]) break;
            aux += 2;
            sz++;
        }

        res = max(res, aux);
    }

    //palindromos de tamanho par

    for(int i = 0;i < n;i++){
        int aux = 0;
        int sz = 0;

        for(int j = i;j >= 0;j--){
            if(v[i-sz] != v[i+sz+1]) break;
            aux += 2;
            sz++;
        }

        res = max(res, aux);
    }

    cout << res << "\n";

    return 0;
}