#include <bits/stdc++.h>

using namespace std;

int main() {
    freopen("BAI2.inp", "r", stdin);
    freopen("BAI2.out", "w", stdout);

    int n;
    cin >> n;

    string s;
    cin >> s;

    int cnt[123], max_count = 0;

    memset(cnt, 0, sizeof(cnt));
    for (int i = 0; i < n; i++) {
        cnt[s[i]]++;
        max_count = max(max_count, cnt[s[i]]);
        cerr << cnt[s[i]] << ' ';
    }   
    
    for (int i = 'a'; i <= 'z'; i++) {
        if (cnt[i] == max_count) {
            cout << char(i) << ' ';
            break;
        }
    }
    return 0;
}