add branch_1
add branch_3
add branch_5
add branch_7
coalesce branch_7 and branch_5 at time 0.484660610121
coalesce branch_1 and branch_3 at time 2.17081331628
coalesce branch_7 and branch_1 at time 4.08913271059
coalesce branch_0 and branch_7 at time 11.4171242866