1st https://iq.opengenus.org/minimum-increment-decrement-equal/
2nd https://www.chegg.com/homework-help/questions-and-answers/write-code-c-also-check-corner-cases-code-giving-error-1-test-case-q92784891
3rd https://forums.phpfreaks.com/topic/313584-assign-values-from-the-range-n-to-the-vertices-of-the-graph/
