#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define sz size()
#define ff first
#define ss second
#define pb push_back
#define pii pair <int, int>
#define dur exit(0)
#define dur1 return(0)
const int N = 2e5 + 5;
char a[N];
int main () {
// freopen ("input.txt", "r", stdin);
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int n;
cin >> n;
for (int i = 1; i <= n; ++i) {
int x;
cin >> x;
a[i] = char(x + 48);
}
for (int i = 1; ; ++i) {
int idx = 0, bol = 0;
for (int j = i; j <= i + n - 1; ++j) {
string jog = to_string(j);
idx++;
int ok = 0;
for (char k : jog) {
if (k == a[idx]) {
ok = 1;
break;
}
}
if (!ok) {
bol = 1;
break;
}
}
if (!bol) {
return cout << i, 0;
}
}
}
