#include <stdio.h>
int main()
{
int i,n;
long int s;
if(n<=10000)
{
if(n==1)
if(n>1)
{
s=0;
for(i=2;i<=n;i++)
{
if(i%2!=0)
s=s+1;
if(i%2==0)
s=s+2;
}
}
}
return 0;
}
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