original graph:
0 --> 3 2 3 
1 --> 3 
2 --> 0 
3 --> 2 
1(0,3) 2(0,2) 3(0,3) 4(1,3) 5(2,0) 6(3,2) 

removing edges connecting 0 to 3
0 --> 2 
1 --> 3 
2 --> 0 
3 --> 2 
2(0,2) 4(1,3) 5(2,0) 6(3,2) 
removing edges with weight greater than 3
0 --> 2 
1 --> 
2 --> 
3 --> 
2(0,2)