Test 1: X X1 X12 X123 X X1 X12 X123
Test 2: 1X 12X 123X 1X 12X 123X
Test 3: 1X 1X2 1X23 1X234 1X 1X2 1X23 1X234
Test 4: X1 1X2 12X3 123X4 X1 1X2 12X3 123X4