//You can never leave
#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
int a1[10]{0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int a2[10]{0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int a3[10]{0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
for (int i = 0; i < n; i++)
{
for (int j = 0; j < 6; j++)
{
int cur;
cin >> cur;
if(i == 0) a1[cur]++;
else if(i == 1) a2[cur]++;
else a3[cur]++;
}
}
int ans = 0;
for (int i = 1; i < 100; i++)
{
bool flag = false;
int temp = i;
pair<int, int> a{0, -1};
while (temp)
{
int cur = temp % 10;
if(a.second == -1)
a.second = cur;
else
a.first = cur;
temp /= 10;
}
if(a.first == 0)
{
if(a1[a.second] || a2[a.second] || a3[a.second])
flag = true;
}
else if(a1[a.first])
{
if(a2[a.second])
flag = true;
else if(a3[a.second])
flag = true;
}
if(a2[a.first])
{
if(a3[a.second])
flag = true;
else if(a1[a.second])
flag = true;
}
if(a3[a.first])
{
if(a1[a.second])
flag = true;
else if(a2[a.second])
flag = true;
}
if(!flag)
{
ans = i - 1;
break;
}
}
cout << ans;
}
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