/**
 * Check if a string contains any character appearing exactly `count` times
 * @param {string} line - The input string to be checked
 * @param {number} [charCount=2] - The required number of occurrences for a character to be considered
 * @returns {boolean} - True if any character appears exactly `charCount` times, false otherwise
 */
function hasExactChars(line = '', charCount = 2) {
    // Count the occurrences of each character in the line
    const charCounts = [...line].reduce(
        (acc, char) => ({ ...acc, [char]: (acc[char] || 0) + 1 }),
        {}
    );
 
    // Check if any character has the required count of occurrences
    return Object.values(charCounts).some((count) => count === charCount);
};
 
// Read input line by line using `readline` function
// Check if each line has any character appearing exactly twice, and print it if so
while (line = readline()) {
    if (hasExactChars(line, 2)) {
        print(line);
    }
}
 

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