题解 | #牛牛学数列#

#include <stdio.h>
int main() {
    int n;
    scanf("%d",&n);//分奇偶，数学思想
    if (0 == n%2) {
        printf("%d",-n/2);
    } else {
        printf("%d",n/2+1);
    }
    return 0;
}