Rajitha has a calculator, which has 10 digits. She want to clean the calculator by removing all the keys and while reassembling it, she interchanged the locations of 3 pairs of keys. For example, if she placed the key ‘3’ in the place of the key ‘7’, she placed the key ‘7’ only in the place of the key ‘3’ and not any other key. All keys that were interchanged corresponded only to numbers. Later, she input some calculations and obtained outputs as provided in the table below. The input is shown in terms of the keys that Kavitapressed, while the output is the output displayed by the calculator.

Output:

1.   95 + 84=128

2.   128 + 64=195

3.   912 + 43=942

4.   178 + 19=192

Which of the following pair of digits is unchanged ?