/*#include <iostream> // cout, endl, cin
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower
#include <iomanip>//fixed,setprecision
#include <limits.n>//INT_MAX
#include <math.n>//M_PI
#include <random>
#include <regex> // 正規表現
#include <time.h>*/
#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
//using mint = modint998244353;
 
template <typename T> bool chmax(T &u, const T z) { if (u < z) {u = z; return true;} else return false; }
template <typename T> bool chmin(T &u, const T z) { if (u > z) {u = z; return true;} else return false; }
#define ll long long
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
typedef pair<int, int> P;
//typedef pair<int, P> q;
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
ll lcm(ll a, ll b){return a * b / gcd(a, b);}
//contain(string s,string v) sにvが含まれるかを判定
template<class T, class U>
bool contain(const std::basic_string<T>& s, const U& v) {
   return s.find(v) != std::basic_string<T>::npos;
}
//回転
void rot(vector<string>& a){  int h=a.size(),w=a[0].size();  vector<string> p(w,string(h,'?'));  swap(a,p);  rep(i,h)rep(j,w)a[j][h-1-i]=p[i][j];}

int main(){
  int a,b,c;
  cin>>a>>b>>c;
  int sum=6;
  if(a==b&&b==c)cout<<a<<endl;
  else if(a==b)cout<<c<<endl;
  else if(a==c)cout<<b<<endl;
  else if(b==c)cout<<a<<endl;
  else cout<<sum-(a+b+c)<<endl;
  return 0;
}