#include <bits/stdc++.h>
 
#define ull unsigned long long int
#define ll long long int
#define vll vector<ll>
#define pll pair<long long, long long>
#define vpll vector < pair<long long,long long> >
#define itr vll::iterator
#define all(c) c.begin(),c.end()
#define pb push_back
#define f first
#define s second
#define mod 1000000007
#define inf 1000000000000000001
 
#define rep(i, n)      for(ll i = 0; i <  n; ++i)
#define repA(i, a, n)  for(ll i = a; i <= n; ++i)
#define repD(i, a, n)  for(ll i = a; i >= n; --i)
 
using namespace std;
 
bool func(const pll &a, const pll &b){
    return a.s < b.s;
}
 
ll power(ll x, ll y) 
{ 
    if (y == 0) 
        return 1; 
    else if (y % 2 == 0) 
        return ((power(x, y / 2)%mod) * (power(x, y / 2)%mod)%mod); 
    else
        return (x * ((power(x, y / 2)%mod) * (power(x, y / 2)%mod)%mod))%mod; 
}
 
ll modInverse(ll a, ll m){
    ll m0 = m;
    ll y = 0, x = 1;
    if (m == 1) return 0;
    while (a > 1){
        ll q = a / m;
        ll t = m;
        m = a % m, a = t;
        t = y;
        y = x - q * y;
        x = t;
    }
    if (x < 0) x += m0;
    return x;
} 

void solve(int t){
    ll n,k,  m;
    cin >> n  >> k >> m;
    ll sm = 0;
    rep(i, n-1){
        ll tmp;
        cin >> tmp;
        sm += tmp;
    }
    ll er = n*m-sm;
    if(er >= 0 && er <= k) cout << er;
    else if(er < 0) cout << 0;
    else cout << -1;
}
 
int main(){
 
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    int t, tmp = 0;
    // cin >> t;
    t = 1;
    while(tmp++ < t){
        // cout << "Case #" << tmp << ": ";
        solve(tmp-1);
        if(t-tmp) cout << "\n";
    }
    return 0;
}
#include<bits/stdc++.h>
#include<cmath>
#define pb push_back
#define ld long double
#define mp make_pair
#define vl vector<ll> 
#define vd vector<double>
#define vld vector<long double>
#define ll long long int
#define pl pair<ll, ll>
#define all(a) a.begin(), a.end()
#define forr(i, n) for(ll i=0; i<n; i++) 
#define forr1(i, n) for(ll i=1; i<=n; i++)
using namespace std;
const ld PI =3.1415926535897923846;
const ll MOD = 1000000007;
const ll N=998244353;
ll power(ll x,ll n){ll res=1;while(n>0){if(n&1) res=res*x%MOD;x=x*x%MOD;n>>=1;}return res;}
ll modinverse(ll a){return power(a, MOD-2);}
void solve()
{
    vl a(4);
    cin>>a[0]>>a[1]>>a[2]>>a[3];
    sort(all(a));
    if(a[3]==a[0]+a[1]+a[2]||a[3]+a[0]==a[1]+a[2])
    	cout<<"Yes";
    else
    	cout<<"No";
}
int main()
{
	#ifndef ONLINE_JUDGE
        // for getting input from input.txt
        freopen("input.txt", "r", stdin);
        // for writing output to output.txt
        freopen("output.txt", "w", stdout);
    #endif
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll test=1;
    //cin>>test;
    while(test--)
    {
        solve();
    }
    cerr << "Time : " << 1000 * ((double)clock()) / (double)CLOCKS_PER_SEC << "ms\n";
}