CodeforceRound #277 Div2 pA Calculating Function

一開始忘惹開int64 .__.

#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<vector>
#include<utility>
#include<map>
#include<set>
#include<queue>
#include<cmath>
using namespace std;
typedef long long int int64;
int main()
{
    int64 n;scanf("%I64d", &n);
    if(n%2==0) printf("%I64d\n", n/2);
    else printf("%I64d\n", -n/2-1);
    return 0;
}