#include <iostream>
#include <string>
#include <cctype>
using namespace std;
 
const int ALPHABET = 26;
 
int main() {
    string line;
    int frequency[ALPHABET] = {0};
    while (getline(cin, line)) {
        if (line.empty()) {
            break;
        }
        for (char ch : line) {
            if (isalpha(ch)) {
                ch = tolower(ch);
                ++frequency[ch - 'a'];
            }
        }
    }
    int maxFreq = 0;
    char maxChar = 'a';
    for (int i = 0; i < ALPHABET; ++i) {
        if (frequency[i] > maxFreq) {
            maxFreq = frequency[i];
            maxChar = i + 'a';
        }
    }
    if (maxFreq > 0) {
        cout << maxChar << endl;
    }
    return 0;
}
 

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

U0FsdXQsIEFtIGZvc3QgbEEgbUFyZQ==

SAlut, Am fost lA mAre