#include <iostream>
using namespace std;
int main() {
int n;
cin >> n;
int smallest = 0, biggest = n + 1, x;
for (int i = 1; i < n; ++i) {
cin >> x;
if (biggest - x >= smallest) {
biggest = x;
} else {
smallest = x;
}
}
if (biggest - smallest >= 2 || smallest - biggest >= 2) {
cout << smallest + 1;
} else if (smallest == 0) {
cout << n;
} else {
cout << 1;
}
}
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