#include <iostream>
#include <vector>
#include <string>
#include <map>
#include <cmath>
#include <limits>
using namespace std;
 
template <typename T>
T average(T _l, T _r)
{
T int_part_l = _l / 2;
T int_part_r = _r / 2;
T fract_part_l = (_l > 0 ? 1 : -1) *(_l % 2);
T fract_part_r = (_r > 0 ? 1 : -1) *(_r % 2);
return int_part_l + int_part_r + (fract_part_l + fract_part_r)/2;
}
 
 
int main() {
    cout << average(-1,1) << endl;
    return 0;
}

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