#include <bits/stdc++.h>
#define sze(x) (ll)x.size()
#define idx(x, a) get<x>(a)
#define pb push_back
#define fi first
#define se second
using namespace std;
typedef long long ll;
const ll MAXN = 1e6 + 3;
const ll INF = 1e18 + 7;
ll a[MAXN], here[MAXN], n, res = 0;
int main()
{
ios_base::sync_with_stdio(0); cout.tie(0);
#ifdef OFFLINE
freopen("input.inp", "r", stdin);
#endif
cin >> n;
for (ll i = 0; i < n; ++i) cin >> a[i];
for (ll i = n - 1; i >= 0; --i)
{
if (here[a[i] - 1]) here[a[i] - 1]--;
else ++res;
here[a[i]]++;
}
cout << res;
}
