#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define ll long long
#define vi vector<int>
#define vll vector<ll>
#define all(a) a.begin(), a.end()
#define f(i, s, e) for (ll i = s; i < e; ++i)
#define fr(i, s, e) for (ll i = s; i > e; --i)
#define vvi vector<vector<int>>
#define pb push_back
template <class T>
void print_v(vector<T> &v)
{
    for (auto x : v)
        cout << x << ' ';
    cout << '\n';
}



#define pii pair<int, int>
#define pll pair<ll, ll>
#define fraction(a)               \
    cout.unsetf(ios::floatfield); \
    cout.precision(a);            \
    cout.setf(ios::fixed, ios::floatfield);
void yes() { cout << "YES\n"; }
void no() { cout << "NO\n"; }



void solve() {
    ll sm =  (10 * 11) / 2;

    ll x;
    f(i, 0, 9) {cin >> x; sm -= x;}
    cout << sm << '\n';
    
}


int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
    int t = 1;
    // cin >> t;
    while (t--)
        solve();
    return 0;
}