#include <bits/stdc++.h>
using namespace std;
#define reps(i, j, n) for(int i = j; i < (int)n; i++)
#define rep(i, n) reps(i, 0, n)
typedef long long int64;

int main()
{
  int N, A[100000], ret;
  cin >> N;
  rep(i, N) cin >> A[i];
  cout << A[0] - 1 << endl;
}