add srm146 div2 problem 1000 (BridgeCrossing)
add srm146 div2 problem 500 (RectangularGrid)
add srm146 div2 problem 250 (YahtzeeScore)
add srm147 div2 problem 250 (CCipher)
add srm147 div2 problem 600 (PeopleCircle)