#include<bits/stdc++.h>
#include<map>
using namespace std;
#define int long long
#define forn(i, a, b) for (int i = a; i < b; i++)
#define vect vector<int>
#define srt(vec) sort(vec.begin(),vec.end())
bool prime(int a)
{
if(a<=1||a%2==0||a%3==0)return 0;
for(int j=5; j*j<=a; j+=6) {
int k=j+2;
if(a%j==0||a%k==0)return 0;
}
return 1;
}
const int N=2e7+10;
//vector<int> vec(N);
void solve()
{
int n;
vect vec(9);
for(int &j:vec)
cin>>j;
srt(vec);
forn(j,0,10)
{
if(vec[j]!=j+1)
{n=j+1;
break;}
}
cout<<n<<endl;
}
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0);

int t = 1;  
//cin >> t;;  
    while (t--)  
        solve();  

    return 0;  
}