predsxxminusx0xminusxsypredminusxyquot0sy0quotsxsysquotminusxysyminusxsyminusxyminusxsypredminusxyquotsxsyminusxyquotsxsyquotminusxysytruequotsxsyquotminusxysytrue1quot231020quot221020minus211020008pred1110s17111quotsxsyminusxyfalseminusxsyminusxytrue1minus201120quot221025minus211021006pred1110s1112minusxsypredminusxyfalse