#include <bits/stdc++.h>
// #define int long long
#define ll long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<char,char> pcc;
typedef pair<pii,int> ipii;
typedef pair<pii,pii> ipiii;
const int MAXN = 3e6+10;
const int MAXA = 1e7+10;
const int SQRT = 300;
const int LOG = 20;
const ld EPS = 1e-6;
const int MOD = 998244353;
int sum(int a, int b){ return (a+b)%MOD; }
void chsum(int &a, int b){ a = (a+b)%MOD; }
void chsub(int &a, int b){ a = (a+MOD-b)%MOD; }
int mul(int a, int b){ return (a*b)%MOD; }
void chmul(int &a, int b){ a = (a*b)%MOD; }
void chmn(int &a, int b){ a = min(a, b); }
void chmx(int &a, int b){ a = max(a, b); }
int n, a[MAXN];
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>n;
multiset<int>m; int ans = 0;
for(int i=1; i<=n; i++){
cin>>a[i];
if(m.find(a[i]) == m.end()){
ans++; m.insert(a[i]-1);
} else {
m.erase(m.find(a[i]));
m.insert(a[i]-1);
}
}
cout << ans << '\n';
}
