please solve it on C language

A number is magical number if repeated adding of its digit gives 1 . Examples: 19 is magical, since 1+9=10,1+0=1 hence magical. 991 is magical, since 9+9+1=19,1+9=10,1+0=1. However 274 is not, 2+7+4=13,1+3=4. Write a program which reads from the user , a list of positive integers,. The program should examine if the number is magical, or not and your program should stop when 1 is entered. You should write a function is_magical which receives a positive integer n and returns 1 if n is a magical number or 0 otherwise