#### You are given two strings A and B. Find the index of the first occurrence of A in B. If A is not present in B, then return -1.

##### For Example:

```
A = “bc”, B = “abcddbc”.
String “A” is present at index 1, and 5(0-based index), but we will return 1 as it is the first occurrence of “A” in string “B”.
```

##### Follow Up:

```
Can you solve this in linear time and space complexity?
```

```
The first line contains an integer 'T' which denotes the number of test cases or queries to be run. Then, the T test cases follow.
The first and only line of each test case contains two strings A and B, separated by a single space.
```

```
For each test case, print the index of the first occurrence of A in B, if string A is not present in string B then print -1.
```

##### Note:

```
You do not need to print anything. It has already been taken care of. Just implement the given function.
```

##### Constraints:

```
1 <= T <= 100
1 <= |A|, |B| <= 5 * 10^4
Time limit: 1 second
```

##### Sample Input 1:

```
2
ninjas codingninjas
code codingninjas
```

##### Sample Output 1:

```
6
-1
```

##### Explanation For Sample Input 1:

```
For the first test case, “ninjas” is present at the 6th index of “codingninjas”.
For the second test case, “code” is not present in “codingninjas”.
```

##### Sample Input 2:

```
2
e add
en engagement
```

##### Sample output 2:

```
-1
0
```