( A [ i ] [ 0 ] , A [ i ] [ 1 ] ) denotes the coordinate of the bottom left of the rectangle ( A [ i ] [ 2 ] , A [ i ] [ 3 ] ) denotes the coordinate of upper right of the rectangle
vector < vector < int > > A = { { 1 , 3 , 4 , 5 } , { 3 , 1 , 7 , 4 } , { 5 , 3 , 8 , 6 } } ;