# Test case 1
{a}
{-1}
# Test case 2
{a{b{c}{d{e}}}{f{g}{h{i{j}{k}}}}{l{m}}}
{-1,0,1,1,3,0,5,5,7,8,8,0,11}
# Test case 3 - a path
{{{{{{{{{{{{{{{{{{{{}}}}}}}}}}}}}}}}}}}}
{-1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18}
# Test case 4 - right-branch tree
{{}{{}{{}{{}{{}{}}}}}}
{-1,0,0,2,2,4,4,6,6,8,8}
# Test case 5 - left-branch tree
{{{{{{}{}}{}}{}}{}}{}}
{-1,0,1,2,3,4,4,3,2,1,0}
# Test case 6
{f{a}{e{c{b}}{d}}}
{-1,0,0,2,3,2}