#include int main(){ int n,i,sum; scanf("%d",&n); for(i=0,sum=0;i sum+=(i+1)*2-1; printf("%d\n",sum); return 0;}
#include int main(){ int n,sum=0; scanf("%d",&n); for(int i=1; i<=n; i+=2) sum +=i; printf("%d\n",sum); return 0;}
