35 lines
665 B
C++
35 lines
665 B
C++
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#include <bits/stdc++.h>
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using namespace std;
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int main() {
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int n;
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cin >> n;
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vector<pair<string, string>>allatok(n);
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set<string>kaja;
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set<string> out;
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for (int i =0; i < n ;i++) {
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cin >> allatok[i].first;
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//cout<<"s";
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cin >> allatok[i].second;
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kaja.insert(allatok[i].first);
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}
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for (int i = 0; i < n;i++) {
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if (kaja.count(allatok[i].second)) {
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//cout<<endl<<allatok[i].second<< " is in the set: "<<kaja.count(allatok[i].second);
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out.insert(allatok[i].first);
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}
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}
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cout<<out.size()<<endl;
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for (string x : out) {
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cout<<x<<endl;
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}
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}
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