+51 Find the number of paths from P to Q, where each step is to the right or up.
$[asy]
draw((0,0)--(2,0)--(2,6)--(6,6));
draw((0,0)--(0,3)--(6,3)--(6,6));
draw((0,1)--(2,1));
draw((0,2)--(2,2)); <#> draw((1,0)--(1,3)); <#> draw((3,6)--(3,3)); <#> draw((4,6)--(4,3)); <#> draw((5,6)--(5,3)); <#> draw((2,4)--(6,4)); <#> draw((2,5)--(6,5)); <#> label("$P$",(0,0),SW); <#> label("$Q$",(6,6),NE); <#> [/asy]$
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