//The Rumbling starts here:
//#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include<bits/stdc++.h>
#define debug(n,m) cout<<"["<<#n<<"]->"<<n<<m
#define int long long
#define all(x) x.begin(),x.end()
#define ai array<int,2>
#define pb push_back
using namespace std;
const int N=316241;
const int mod=1e9+7;
const int inf=(1ll<<55)-1;
int a[N],b[N];
void levi() {
//#define tests
int n;
cin>>n;
for (int i=1;i<=n;i++) {
cin>>a[i];
}
multiset<int> ms;
for (int i=n;i;i--) {
if (ms.count(a[i]-1)) {
ms.erase(ms.find(a[i]-1));
}
ms.insert(a[i]);
}
cout<<ms.size()<<'\n';
}
int32_t main() {
//freopen("input.in","r",stdin);
ios_base::sync_with_stdio(0);
cin.tie(0);
int tt=1;
#ifdef tests
cin>>tt;
#endif
while(tt--) levi();
}
