using namespace std;
int main(){
	int n,ans=0;
	cin>>n;
	for(int i=1;i<=n;i++){
		if(i%2==0){
			ans-=i;
		}else if(i%2!=0){
			ans+=i;
		}
	}
	cout<<ans<<endl;
	return 0;
}

using namespace std;

int main(){
int n; 
cin >> n; 
if(n%2==0){ 
cout << n/2*-1 << endl;
} 
else{ 
cout<<(n-1)/2*(-1)+n;
}
}

#include <iostream> using namespace std;

int main() { int n; cin >> n; if(n%2==0) { cout << n/2*-1 << endl; } else { cout << (n-1)/2*(-1)+n; }

return 0;

}

#include <bits/stdc++.h>

using namespace std;

int main(){

int sum=0;

int n;

cin>>n;

for(int i=1;i<=n;i+=2){

sum+=i;

}

for(int i=2;i<=n;i+=2){

sum-=i;

}

cout<<sum;

}