#include "iostream"
using namespace std;
int main()
{
int num=1,flag=1,sum=0;
while(num<=101)
{
sum = sum+num*flag;
num += 2;
flag = -flag;
}
cout << sum << endl;
return 0;
}
#include
int main()
{int i,s=0;
for(i=1;i<102;i+=2)
s+=i%4==1?i:-i;
printf("%d\n",s);
return 0;
}