Problema 1
#include <iostream>
using namespace std;
int main()
{
int n, suma, x;
cin>>n;
int copie=n;
while( copie != 0 )
{
cin>>x;
if ( x % 3 == 0 )
suma = suma + x;
copie--;
}
cout<<suma;
}
Problema 2
#include <iostream>
using namespace std;
int main()
{
int n, i=1;
cin>>n;
while(i<=n)
{
cout<<i<<" ";
i++;
}
}