Dots, ka \(x_{1}, x_{2}, x_{3}, x_{4}\) - pozitīvi skaitļi. Pierādi, ka

\[\frac{x_{1}+x_{3}}{x_{1}+x_{2}}+\frac{x_{2}+x_{4}}{x_{2}+x_{3}}+\frac{x_{3}+x_{1}}{x_{3}+x_{4}}+\frac{x_{4}+x_{2}}{x_{4}+x_{1}} \geq 4\]