Call 1st Character

2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - A - C - D - E - F - G - H - I - J - K - L - M - N - O - P - R - S - T - U - V - W - X - Y - Z

Find your prefix

5C5 - 5M2 - 5N2