#include <iostream>
using namespace std;
bool isValidNr(int nr) {
int fstDig = nr / 100, secDig = nr / 10 % 10, lastDig = nr % 10;
return nr >= 100 && nr <= 999 && fstDig < secDig && secDig < lastDig;
}
int findValidNr(int frq[]) {
for (int currNr = 100; currNr <= 999; ++currNr) {
if (frq[currNr] == 1) {
return currNr;
}
}
return 0;
}
int main() {
int n, frq[1000] = {0};
cin >> n;
for (int i = 1; i <= n; ++i) {
int currEl;
cin >> currEl;
if (isValidNr(currEl)) {
++frq[currEl];
}
}
cout << findValidNr(frq);
return 0;
}
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