мы с конём вдвоём по полю пойдём

#include <iostream>
#include <fstream>
#include <vector>

int search(int x1, int y1, int& x2, int& y2, int& temp) {

    if (x1 == 0 || y1 == 0) {
        return 0;
    }

    if (x1 == x2 && y1 == y2 && temp < 3 && temp > 0) {
        return 1;
    }

    temp++;

    int x = 1, y = 2;

    if (temp < 3) {
        for (int i = 0; i < 2; i++) {
            if (search(x1 + x, y1 + y, x2, y2, temp) != 0) {
                return temp;
            }
            if (search(x1 - x, y1 - y, x2, y2, temp) != 0) {
                return temp;
            }
            if (search(x1 + x, y1 - y, x2, y2, temp) != 0) {
                return temp;
            }
            if (search(x1 - x, y1 + y, x2, y2, temp) != 0) {
                return temp;
            }
            std::swap(x, y);
        }
    }

    temp--;

    return 0;

}

int main() {

    std::ifstream fin("input.txt");
    std::ofstream fout("output.txt");

    std::string s1, s2;

    fin >> s1 >> s2;

    int x1 = s1[0] - 'a' + 1, y1 = s1[1] - '0',
        x2 = s2[0] - 'a' + 1, y2 = s2[1] - '0';
    int temp = 0;
    int k = search(x1, y1, x2, y2, temp);

    if (k != 0) {
        fout << k << std::endl;
        return 0;
    }

    fout << "NO" << std::endl;
    return 0;

}