#include <bits/stdc++.h>
using namespace std;
const int inf = 0x3f3f3f3f;
const int _inf = 0xc0c0c0c0;
const long long INF = 0x3f3f3f3f3f3f3f3f;
const long long _INF = 0xc0c0c0c0c0c0c0c0;
const long long mod = (int)1e9 + 7;
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long ksm(long long a, long long b, long long mod) {
  int ans = 1;
  while (b) {
    if (b & 1) ans = (ans * a) % mod;
    a = (a * a) % mod;
    b >>= 1;
  }
  return ans;
}
long long inv2(long long a, long long mod) { return ksm(a, mod - 2, mod); }
long long arr[1000025];
int main() {
  int n;
  long long m;
  scanf("%d%lld", &n, &m);
  for (int i = 1; i <= n; ++i) scanf("%lld", &arr[i]);
  sort(arr + 1, arr + 1 + n);
  long long ans = 0, maxx = arr[n], tmp = 0;
  for (int i = 1; i < n; ++i) {
    ans += arr[i] - 1;
    tmp = min(arr[i], tmp + 1);
  }
  if (maxx > tmp)
    ans += arr[n] - (maxx - tmp);
  else
    ans += arr[n] - 1;
  printf("%lld\n", ans);
  return 0;
}
