#include <iostream>
#include <string>
#include <vector>
#include <deque>
#include <queue>
#include <algorithm>
#include <iomanip>
#include <set>
#include <map>
#include <bitset>
#include <cmath>
#include <functional>

using namespace std;

#define REP(i,n) for(ll (i) = (0);(i) < (n);++i)
#define REV(i,n) for(ll (i) = (n) - 1;(i) >= 0;--i)
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define FI first
#define SE second
#define ALL(v) v.begin(),v.end()
#define Decimal fixed<<setprecision(20)
#define INF 1000000000
#define LLINF 1000000000000000000LL
#define MOD 1000000007LL

typedef long long ll;
typedef pair<ll,ll> P;

template<typename T>
void show_vector(vector<T> v) {
	for (auto ele: v)cout << ele << " " ;cout << endl;
}

template<typename T>
void show_vector(vector<vector<T>> v) {
	for (auto ele: v)show_vector(ele);
}

template<typename T>
void show_vector(vector<vector<vector<T>>> v) {
	for (auto ele: v) {
		show_vector(ele);
		cout << endl;
	}
}

int main(){
	cin.tie(0);cout.tie(0);ios::sync_with_stdio(false);

	ll n, m;cin >> n >> m;
	map<int, int> mp;
	REP(i, n) {
		ll a;cin >> a;mp[a]++;
	}
	REP(i, m) {
		ll b;cin >> b;mp[b]++;
	}

	for(auto ele: mp) {
		if(ele.SE == 1)cout << ele.FI << " ";
	}
	cout << endl;


	return 0;
}

//~ while (clock()<=69*CLOCKS_PER_SEC)
//~ #pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("O3")
//~ #pragma GCC target ("avx2")
//~ #pragma GCC optimize("Ofast")
//~ #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//~ #pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename \
  enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
    *this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
#else
sim dor(const c&) { ris; }
#endif
};
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "

#define shandom_ruffle random_shuffle

using ll=long long;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
using vi=vector<int>;
using vll=vector<ll>;
const int nax=1000*1007;

int n;
char wcz[nax];

int main()
{
	scanf("%d", &n);
	scanf("%s", wcz+1);
	int row=1;
	for (int i=1; i<=n; i++)
	{
		if (wcz[i]!=wcz[1])
			row=0;
	}
	int wyn=nax;
	if (wcz[1]!=wcz[n])
		wyn=1;
	for (int i=2; i<n; i++)
	{
		if (wcz[i]!=wcz[1] && wcz[i+1]!=wcz[1])
			wyn=min(wyn, 2);
	}
	if (wyn==nax)
		wyn=-1;
	printf("%d\n", wyn);
	return 0;
}
