process.stdin.resume();
process.stdin.setEncoding('utf8');
 
// your code goes here
var readline = require("readline");
 
function filterWord(callback) {
    return function (line) {
        var words = line.match(/\S+/g) || [];
        words.forEach(callback);
    };
}
 
function main() {
    var rl = readline.createInterface(process.stdin, process.stdout);
 
    var seen = {};
    rl.on('line', filterWord(function(word) {
        if (word in seen) return;
        seen[word] = true;
        console.log(word);
    }));
}
main()

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