Răspuns :
COROANA TE ROG!!!
1
#include<iostream>
using namespace std;
int main(){
int n;
cin>>n;
cout<<(n*(n+1))/2;
return 0;
}
2
#include<iostream>
using namespace std;
int main(){
int n;
cin>>n;
cout<<n*(n+1);
return 0;
}
3
#include<iostream>
using namespace std;
int main(){
int n;
cin>>n;
if(n%2==0) cout<<n/2;
else cout<<n/2+1;
return 0;
}