The test file for undirected graph

It has 64 nodes and the pair below indicates edges undirected.

first.txt

@@ -0,0 +1,267 @@
+64
+1	11
+1	13
+1	18
+1	37
+1	43
+1	53
+1	56
+2	9
+2	15
+2	17
+2	35
+2	38
+2	45
+2	53
+2	61
+3	7
+3	8
+3	10
+3	16
+3	21
+3	36
+3	63
+6	10
+6	11
+6	13
+6	15
+6	16
+6	18
+6	37
+6	43
+6	56
+6	60
+7	8
+7	10
+7	14
+7	16
+7	18
+7	36
+7	59
+7	63
+8	10
+8	12
+8	14
+8	16
+8	19
+8	21
+8	23
+8	25
+8	27
+8	30
+8	32
+8	33
+8	34
+8	36
+8	41
+8	42
+8	49
+8	50
+8	51
+8	52
+8	55
+8	58
+8	59
+8	63
+9	17
+9	35
+9	53
+9	61
+10	14
+10	16
+10	18
+10	19
+10	21
+10	27
+10	32
+10	34
+10	36
+10	37
+10	49
+10	51
+10	52
+10	55
+10	56
+10	59
+10	60
+10	63
+11	13
+11	15
+11	18
+11	37
+11	38
+11	43
+11	56
+11	60
+12	59
+12	63
+13	15
+13	17
+13	22
+13	35
+13	37
+13	38
+13	43
+13	53
+13	56
+13	60
+13	61
+14	16
+14	19
+14	21
+14	27
+14	36
+14	51
+14	52
+14	59
+14	63
+15	17
+15	35
+15	38
+15	43
+15	53
+15	61
+16	18
+16	19
+16	21
+16	23
+16	25
+16	27
+16	32
+16	33
+16	34
+16	36
+16	37
+16	49
+16	51
+16	52
+16	55
+16	56
+16	58
+16	59
+16	60
+16	63
+17	22
+17	35
+17	38
+17	45
+17	53
+17	61
+18	36
+18	37
+18	43
+18	55
+18	56
+18	60
+19	21
+19	23
+19	25
+19	27
+19	32
+19	33
+19	34
+19	36
+19	49
+19	51
+19	52
+19	58
+19	59
+19	63
+21	23
+21	25
+21	27
+21	32
+21	33
+21	34
+21	36
+21	49
+21	51
+21	52
+21	59
+21	63
+22	35
+22	38
+22	53
+23	27
+23	33
+23	36
+23	51
+23	52
+23	59
+23	63
+25	30
+25	36
+25	51
+25	59
+25	63
+27	30
+27	32
+27	33
+27	34
+27	36
+27	49
+27	51
+27	52
+27	59
+27	63
+32	33
+32	34
+32	36
+32	49
+32	51
+32	52
+32	59
+32	63
+33	36
+33	49
+33	51
+33	52
+33	54
+33	59
+33	63
+34	36
+34	49
+34	51
+34	52
+34	59
+34	63
+35	38
+35	45
+35	46
+35	53
+35	61
+36	37
+36	49
+36	51
+36	52
+36	55
+36	58
+36	59
+36	60
+36	63
+37	43
+37	56
+37	60
+38	43
+38	53
+38	61
+42	51
+42	63
+43	56
+43	60
+49	51
+49	52
+49	59
+49	63
+51	52
+51	59
+51	63
+52	58
+52	59
+52	63
+53	61
+55	63
+56	60
+58	59
+58	63
+59	63