#include <bits/stdc++.h>
using namespace std;
// Do you think you'll ever remember me someday, or will I just fade away from your memory?
#define LIFESUCK ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define ll long long
#define str string
#define mll map<ll, ll>
#define vll vector<ll>
#define pll pair<ll, ll>
#define fi first
#define se second
#define all(c) c.begin(), c.end()
#define pb push_back
#define debug cout << "I Love You\n";
#define fu(i, a, b) for (int i = a; i <= b; i++)
#define fd(i, b, a) for (int i = b; i >= a; i--)
#define Bitc(msk, j) ((msk >> j) & 1)
#define _log(x) 31 - __builtin_clz(x)
const ll Mod = 1e9 + 7;
const ll inf = (1ll << 30);
const ll lnf = (1ll << 60);
// When time passes and things change... will you still remember someone like me?
int64_t add(ll &a, ll b) {
a += b;
if (a >= Mod) a %= Mod;
while (a < 0) a += Mod;
return a;
}
int64_t mul(ll a, ll b) {
a = 1ll * a * b % Mod;
return a;
}
template <class X, class Y>
bool minimize(X &x, Y y) {
X eps = 1e-9;
if (x > y + eps) {
x = y;
return 1;
}
return 0;
}
template <class X, class Y>
bool maximize(X &x, Y y) {
X eps = 1e-9;
if (x + eps < y) {
x = y;
return 1;
}
return 0;
}
// I wonder… will I just become a distant memory to you one day?
#define mxn 200'007
ll n, len;
str s;
vll graph[mxn];
struct Edge{
ll u, v;
} edge[mxn];
namespace Love1 {
bool check () {
return (n <= 3000);
}
vector<char> t;
const ll base = 37;
bool dfs(ll u, ll p, ll end) {
if(u == end) return 1;
for(auto&v: graph[u]) {
if(v == p) continue;
if(dfs(v, u, end)) { t.pb(s[v]); return 1;}
}
return 0;
}
ll get(){
ll sad = 0;
for(auto&i: t) sad = (sad * base + i) % Mod;
return sad;
}
ll getReverse(){
ll sad = 0;
fd(i, t.size() - 1, 0) sad = (sad * base + t[i]) % Mod;
return sad;
}
void DreamyLove () {
ll sad = 1;
fu(u, 1, n) {
fu(v, u + 1, n) {
t.clear();
dfs(u, 0, v); t.pb(s[u]);
// cerr << u << ' ' << v << '\n';
// for(auto&i: t) cerr << i;
// cerr << '\n' << '\n';
if(get() == getReverse()) maximize(sad, t.size());
}
}
cout << sad;
}
}
void lovesper(const ll &TestCase) {
cin >> n >> s;
len = s.size(); s = '#' + s;
fu(i, 2, n) {
ll u, v; cin >> u >> v;
graph[u].pb(v);
graph[v].pb(u);
edge[i] = {u, v};
}
if(Love1::check()) {
Love1::DreamyLove();
return;
}
}
signed main() {
LIFESUCK
#define name "lovesper"
// freopen(name".inp", "r", stdin);
// freopen(name".out", "w", stdout);
ll Test = 1;
// cin >> Test;
fu(i, 1, Test) {
lovesper(i);
if (i < Test) cout << '\n';
}
return 0;
}
