#include using namespace std; #pragma GCC optimize("Ofast") #define rep(i,n) for(ll i=0;i=0;i--) #define perl(i,r,l) for(ll i=r-1;i>=l;i--) #define fi first #define se second #define pb push_back #define ins insert #define pqueue(x) priority_queue,greater> #define all(x) (x).begin(),(x).end() #define CST(x) cout<; using vvl=vector>; using pl=pair; using vpl=vector; using vvpl=vector; const ll MOD=1000000007; const ll MOD9=998244353; const int inf=1e9+10; const ll INF=4e18; const ll dy[8]={1,0,-1,0,1,1,-1,-1}; const ll dx[8]={0,1,0,-1,1,-1,1,-1}; template inline bool chmax(T &a, T b) { return ((a < b) ? (a = b, true) : (false)); } template inline bool chmin(T &a, T b) { return ((a > b) ? (a = b, true) : (false)); } struct UnionFind { vector par; vector edge; UnionFind(int n) : par(n, -1),edge(n, 0) {} int root(int x) { if (par[x] < 0) return x; else return par[x] = root(par[x]); } bool same(int x, int y) { return root(x) == root(y); } bool merge(int x, int y) { x = root(x); y = root(y); if (x == y) { edge[x]++; return false; } if (par[x] > par[y]) swap(x, y); par[x] += par[y]; par[y] = x; edge[x] += edge[y]+1; return true; } int size(int x) { return -par[root(x)]; } }; int main(){ ios::sync_with_stdio(false); std::cin.tie(nullptr); ll p=0;rep(i,11)p^=i; rep(i,9){ ll a;cin >> a;p^=a; } cout << p << endl; }