#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ar array
#define vo vector
#define pb push_back
#define all(x) begin(x), end(x)
#define sz(x) (ll)(x).size()
#define rep(i, a, b) for(ll i=a; i<b; i++)
#define repd(i, a, b) for(ll i=a; i>=b; i--)
int main() {
cin.tie(0)->sync_with_stdio(0);
ll n;
cin >> n;
ll cnt[ll(1e6+1)];
memset(cnt, 0, sizeof cnt);
rep(i, 0, n) {
ll a;
cin >> a;
if(!cnt[a])
cnt[a-1]++;
else {
cnt[a]--;
cnt[a-1]++;
}
}
ll ans=0;
rep(i, 0, ll(1e6+1))
ans+=cnt[i];
cout << ans << "\n";
}
