const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;
void (async function () {
const n = Number(await readline());
const map = new Map();
for (let i = 0; i < n; i++) {
const [child, parent] = (await readline()).split(" ");
map.set(child);
map.set(parent, map.get(parent) ? [...map.get(parent), child] : [child]);
}
const node = await readline();
const res = [];
const dfs = (node) => {
if (map.has(node)) {
if (!map.get(node)) return;
for (let i = 0; i < [...map.get(node)].length; i++) {
const child = [...map.get(node)][i];
res.push(child);
dfs(child);
}
}
};
dfs(node);
res.sort().forEach((val) => {
console.log(val);
});
})();