C++ :

#include<bits/stdc++.h>
using namespace std;
int n,a[100005],ans;
int main()
{
//	freopen("691.in","r",stdin);
//	freopen("691.out","w",stdout);	
	cin>>n;
	for(int i=0;i<n;i++)
		cin>>a[i];
	sort(a,a+n);
	a[n]=a[n-1]+1;
	for(int i=0;i<n;i++)
		if(a[i]!=a[i+1]) ans++;
	cout<<ans;
    return 0;
}