#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
const int N = 1000006;
int n;
int a[N];
bool color[N];
int main()
{
ios_base::sync_with_stdio(false);
cin >> n;
for (int i = 0; i < n; i++)
cin >> a[i];
int ans = 1;
bool f = false;
for (int i = n - 1; i > 0; i--) {
color[a[i]] = true;
if (a[i] == a[i - 1] + 1)
continue;
if (a[i - 1] > a[i]) {
ans++;
f = false;
continue;
}
for (int j = a[i - 1] + 1; j <= a[i]; j++) {
if (j == a[i]) {
if (f)
ans++;
f = true;
break;
}
if (!color[j]) {
ans++;
f = false;
break;
}
}
}
cout << ans << endl;
return 0;
}
