题解 | #牛牛学数列#

#include <stdio.h>

int main()
 {
    int m,n,o,p;
    int sum1=0;
    int sum2=0;
    int sum3=0;
    scanf("%d",&n);
    for(m=1;m<=n;m++)
    {
        if(m%2==0)
        {   o=m/2;
            sum2=sum2+2*o;
        }
        else{
            p=(m+1)/2;
        sum1=sum1+2*p-1;
    }}
    sum3=sum1-sum2;
    printf("%d",sum3);    
    
    return 0;
}