The international standard letter/number mapping for telephones is:{A, B, C} -> 2{D, E, F} -> 3{G, H, I} -> 4{J, K, L} -> 5{M, N, O} -> 6{P, Q, R, S} -> 7{T, U, V} -> 8{W, X, Y, Z} -> 9Write a functiongetNumber()that takes an upper case letter and returns thenumber according to the international standard above. Write a test program that prompts the user to enter a phone number as a string. The input number may contain letters. The program translates a letter (uppercaseor lowercase) to a digit and leaves all other characters intact. Here are sample runs of the program:Enter a string: 1-800- Flowers1 -800 -3569377Enter a string: 1800 flowers18003569377