# A lower triangular matrix
# 2 0 0 0
# 2 1 0 0 
# 3 2 1 0
# 4 3 2 4
4 4 10
0 0 2
1 0 2
1 1 1
2 0 3
2 1 2
2 2 1
3 0 4
3 1 3
3 2 2
3 3 4
