Răspuns:
1.#include <iostream>
using namespace std;
int n,a,S;
int main()
{cin>>n;
while(a<=n)
{S=S+a;
a++;}
cout<<S;
return 0;
}
2.#include <iostream>
using namespace std;
int n,a,S;
int main()
{cin>>n;
a=1;
while(a<=n)
{S=S+a;
a=a+2;}
cout<<S;
return 0;
}