//author:pandaoxi
#include <iostream>
using namespace std;
int main(){
	int n,m=0;
	cin>>n;
	for(int i=1;i<=n;i++){
		if(i%2) m+=i;
	}
	cout<<m<<endl;
	return 0;
}

//author:pandaoxi
#include <iostream>
#include <cmath>
using namespace std;
int main(){
	int n,a[31]={},k=0;
	cin>>n;
	for(int i=1;i<=n;i++){
		a[k++]=pow(i,2);
	}
	for(int i=0;i<k-1;i++){
		cout<<a[i]<<',';
	}
	cout<<a[k-1]<<endl;
	return 0;
} 

//author:pandaoxi
#include <iostream>
using namespace std;
int main(){
	int n;
	cin>>n;
	if(n%2) cout<<1<<endl;
	else cout<<0<<endl;
	return 0;
} 

//author:pandaoxi
#include <iostream>
#include <cstring>
using namespace std;
int main(){
	char a[10001];
	cin>>a;
	cout<<strlen(a)<<endl;
	return 0;
} 

//author:pandaoxi
#include <iostream>
using namespace std;
int main(){
	int m,n,k=0,a[10001];
	cin>>m>>n;
	for(int i=m;i<=n;i++){
		if(i%5&&i%7==0) a[k++]=i;
	}
	for(int i=0;i<(k-1);i++){
		cout<<a[i]<<",";
	}
	cout<<a[k-1]<<endl;
	return 0;
}