#include <iostream>
using namespace std;
const int MAX_SIZE = 1000;
int main() {
int dataSize, sentData = 0;
cin >> dataSize;
for (int i = 0; i < dataSize; ++i) {
int currentData;
cin >> currentData;
sentData += currentData;
}
for (int i = 0; i < dataSize - 1; ++i) {
int currentData;
cin >> currentData;
sentData -= currentData;
}
cout << sentData;
return 0;
}
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