UVa 11401

#include<bits/stdc++.h>
using namespace std;

typedef long long int       ll;
typedef unsigned long long int  ull;
typedef vector<int>         vi;
typedef vector<ll>          vll;
typedef vector<vi>          vvi;
typedef pair<int,int >      pii;
typedef vector< pii >       vpii;
typedef set<int>            sti;

#define sc                  scanf
#define pf                  printf
#define sci(n)              scanf("%d",&n)
#define scl(n)              scanf("%lld",&n)
#define scf(n)              scanf("%lf",&n)
#define scs(s)              scanf("%s",s)
#define pfi(n)              printf("%d",n)
#define pfl(n)              printf("%lld",n)
#define pff(n)              cout<<n
#define line                printf("\n")
#define spc                 printf(" ")
#define loop(i,x,y)         for(int i=int(x); i<=int(y); i++)
#define rloop(i,y,x)        for(int i=int(y); i>=int(x); i--)
#define cspf(i)             printf("Case %d: ", i)
#define pb                  push_back
#define mp                  make_pair
#define ff                  first
#define ss                  second
#define all(v)              v.begin(),v.end()
#define rall(v)             v.rbegin(),v.rend()
#define read()              freopen("input.txt", "r", stdin)
#define write()             freopen("output.txt", "w", stdout)
/// Constants
#define eps                 1e-9
#define PI                  acos(-1.0)  // 3.1415926535897932

ll tri[1000009];
ll sum[1000009];

void triangle()
{
    sum[1]=1;
    sum[2]=2;
    loop(i,3,1000000){
        sum[i]=i+sum[i-2];
    }
    tri[3]=0;
    loop(i,4,1000001){
        ll cnt=sum[i-3];
        tri[i]=cnt+tri[i-1];
    }
}

int main()
{
    triangle();
    int n;
    while(1){
        sci(n);
        if(n<3) break;
        pfl(tri[n]);line;
    }
    return 0;
}