Gurobi 5.0.1 (linux64) logging started Wed Apr 24 01:32:56 2013

Optimize a model with 36660 rows, 36060 columns and 144060 nonzeros
Presolve removed 3189 rows and 0 columns
Presolve time: 0.22s
Presolved: 33471 rows, 36060 columns, 137682 nonzeros
Variable types: 36000 continuous, 60 integer (60 binary)

Root relaxation: objective 6.820612e+04, 7615 iterations, 1.15 seconds

    Nodes    |    Current Node    |     Objective Bounds      |     Work
 Expl Unexpl |  Obj  Depth IntInf | Incumbent    BestBd   Gap | It/Node Time

     0     0 68206.1159    0    3          - 68206.1159     -      -    1s
H    0     0                    69255.000000 68206.1159  1.51%     -    1s
H    0     0                    68774.000000 68206.1159  0.83%     -    1s
     0     0 68206.1355    0    4 68774.0000 68206.1355  0.83%     -    1s
     0     0 68206.1355    0    4 68774.0000 68206.1355  0.83%     -    2s
H    0     0                    68606.576271 68206.1355  0.58%     -    2s
H    0     0                    68487.000000 68206.1355  0.41%     -    2s
     0     2 68210.3369    0    4 68487.0000 68210.3369  0.40%     -    3s
*    7     3               5    68454.000000 68314.5046  0.20%   111    3s
*   21     0               6    68446.000000 68446.0000   0.0%  96.2    4s

Cutting planes:
  Gomory: 1
  Flow cover: 2

Explored 22 nodes (9639 simplex iterations) in 4.14 seconds
Thread count was 1 (of 16 available processors)

Optimal solution found (tolerance 1.00e-04)
Best objective 6.844600000000e+04, best bound 6.844600000000e+04, gap 0.0%