#include <iostream>
using namespace std;
int main()
{ int max = 30, evenNum;
/* Odd or even? */
if((max % 2)==1)
evenNum = 0;
else
evenNum = 1;
if(evenNum==1)
{
for(int x=1; x<=max; x++)
{
{
cout << x << " " << (max/2)+x << endl;
if (x >= (max/2))
break;
}
}
}
else
for(int x=1; x<=(max+1); x++)
{
{
if(x == ((max+1)/2))
cout << x << endl;
else
cout << x << " " << ((max+1)/2)+x << endl;
if (x >= ((max+1)/2))
break;
}
}
return 0;
}
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