make: 'atpg' is up to date.
========================
parsing file ./benchmark/b20.bench ... Done.
====== Circuit Statistics ====== 
PI:	522
PO:	512
Gate:	8734
Stem:	3428
Level:	7
================================ 
[SOL] flip: 0, stem: 0, fault:49107. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3179
coverage: 18.199%	pattern: 1	before: 17468	now: 14289
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:28816. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3009
coverage: 27.908%	pattern: 2	before: 14289	now: 12593
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:31154. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3635
coverage: 37.423%	pattern: 3	before: 12593	now: 10931
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:7652. flip_cnt: 0, stem_cnt: 3428, fault_cnt:2945
coverage: 39.873%	pattern: 4	before: 10931	now: 10503
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:3885. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3014
coverage: 41.127%	pattern: 5	before: 10503	now: 10284
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:5760. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3259
coverage: 42.896%	pattern: 6	before: 10284	now: 9975
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:1034. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3045
coverage: 43.222%	pattern: 7	before: 9975	now: 9918
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:1011. flip_cnt: 0, stem_cnt: 3428, fault_cnt:2979
coverage: 43.537%	pattern: 8	before: 9918	now: 9863
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:381. flip_cnt: 0, stem_cnt: 3428, fault_cnt:2987
coverage: 43.657%	pattern: 9	before: 9863	now: 9842
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:10489. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3399
coverage: 46.823%	pattern: 10	before: 9842	now: 9289
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:153. flip_cnt: 0, stem_cnt: 3428, fault_cnt:2905
coverage: 46.874%	pattern: 11	before: 9289	now: 9280
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:5681. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3417
coverage: 48.586%	pattern: 12	before: 9280	now: 8981
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:63. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3038
coverage: 48.615%	pattern: 13	before: 8981	now: 8976
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:57. flip_cnt: 0, stem_cnt: 3428, fault_cnt:2944
coverage: 48.632%	pattern: 14	before: 8976	now: 8973
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:76. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3002
coverage: 48.655%	pattern: 15	before: 8973	now: 8969
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:23. flip_cnt: 0, stem_cnt: 3428, fault_cnt:2898
coverage: 48.666%	pattern: 16	before: 8969	now: 8967
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:57. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3189
coverage: 48.683%	pattern: 17	before: 8967	now: 8964
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:0. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3016
coverage: 48.683%	pattern: 17	before: 8964	now: 8964
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:0. flip_cnt: 0, stem_cnt: 3428, fault_cnt:2987
coverage: 48.683%	pattern: 17	before: 8964	now: 8964
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:38. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3030
coverage: 48.695%	pattern: 18	before: 8964	now: 8962
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:0. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3133
coverage: 48.695%	pattern: 18	before: 8962	now: 8962
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:874. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3187
coverage: 48.958%	pattern: 19	before: 8962	now: 8916
checking valid circuit ... result: 1.
[SOL] flip: 0, stem: 0, fault:0. flip_cnt: 0, stem_cnt: 3428, fault_cnt:3076
coverage: 48.958%	pattern: 19	before: 8916	now: 8916
checking valid circuit ... result: 1.