#include<bits/stdc++.h>
// #include<iostream>
// #include<algorithm>
// #include<vector>
// #include<set>
// #include<queue>
// #include<map>
using namespace std;


#define ll long long
#define ld long double

#define For(n) for(ll i=0;i<n;i++)
#define Forr(a,b) for(ll i=a;i<b;i++)

#define sortt(x) sort(x.begin(),x.end())
#define rsortt(x) sort(x.rbegin(),x.rend())
#define condsortt(x) sort(x.begin(),x.end(),sortBy)

#define MOD 1000000007
#define en "\n"


#define F first
#define S second


#define input(x,n) for(ll i=0;i<n;i++) cin>>x[i]
#define v(A,n) vector<ll> A(n)
#define vi(x) vector<ll> x
#define pb(x) push_back(x)
#define MP make_pair
#define PI 3.14159265


void print(vector<ll> vec)
{
    for(auto itr:vec)
        cout<<itr<<" ";
    cout<<en;
}


void solve()
{
    ll a,b,c;
    cin>>a>>b>>c;
    if(a==b)
        cout<<c;
    else if(b==c)
        cout<<a;
    else if(a==c)
        cout<<b;
    else
    cout<<0;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    ll t=1;
    // cin>>t;
    for(ll i=1;i<=t;i++)
    {
        // cout<<"Case #"<<i<<": ";
        solve();
    }
    return 0;
}
#include<bits/stdc++.h>
using namespace std;
using namespace std::chrono;
 
#define IOS ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define ll long long
#define rep(i,a,b)    for(int i=a;i<b;i++)
#define repn(i,a,b)   for(int i=a;i>=b;i--)
#define ff first
#define ss second
#define lb lower_bound
#define ub upper_bound
#define pii pair<int,int>
#define vi vector<int>
#define vii vector<pii>
#define vvi vector<vector<int>>
#define mi  map<int,int>
#define mii map<pii,int>
#define pb push_back
#define ppb pop_back
#define pf push_front
#define ppf pop_front
#define sz(x) (int)x.size()
#define all(v) (v).begin(), (v).end()
#define ret(x) return cout<<x,0;
#define rety return cout<<"YES",0;
#define retn return cout<<"NO",0;
#define fl fflush(stdout)   
#define hell 1000000007
#define hell2 998244353 
#define pi 3.14159265358979323846
 
int fexp(int a, int b,int m){int ans = 1;while(b){if(b&1)ans=ans*a%m; b/=2;a=a*a%m;}return ans;}
int inverse(int a, int p){return fexp(a, p-2,p);} 
 
int fac[300005]; //fac[0]=0;fac[1]=1;rep(i,2,300005)fac[i]=(fac[i-1]+fac[i-2])%hell;
 
int ncr(int n, int r,int p) { 
    if (r==0) return 1; 
    return (fac[n]*inverse(fac[r],p)%p*inverse(fac[n-r],p)%p)%p; 
}
void code_hunter(){
    int n,m;cin>>n>>m;
    if((min(n,m)+3)>max(n,m))
         cout<<"Yes";
    else
        cout<<"No";
}
 signed main(){
    IOS;
    int t=1;
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r" , stdin);
    freopen("output.txt", "w", stdout);
    #endif
    // cin>>t;
    while(t--){
        code_hunter();
       // cout<<"\n";
    }
    return 0;
}