What is the Big-O notation that can best describe the following algorithm?

procedure Alg2(x, A): A is a list of n integers

1    i = 0

2    while (i < n)

3        if (x == A[i])

4            break

5        end of if

6        i = i + 1

7    end of while

8    if (i < n)

9        location = i

a    else

b        location = -1

c    end of if

d    return location