方格纸
/in {72 mul} def
/delta {1 in 10 div} def
/X 612 def
/Y 792 def
0 delta Y {
0 1 index X exch % i 0 X i
moveto exch % 0 i
lineto
stroke
} for
0 delta X {
0 1 index Y % i 0 i Y
moveto % i 0
lineto
stroke
} for
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