Wikipedia calls it DTD-1 for some reason, but IBM sources consistently
if (n <= 1) return;
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（四）购进农产品时，除取得增值税专用发票或者海关进口增值税专用缴款书外，按照农产品收购发票或者农产品销售发票计算的进项税额，国务院另有规定的除外；
When a crash happens, we don’t just get an error message. We get a crash log containing the initial input and the execution trace complete with all outputs.