C 입력된 값 확인 do ~ while

#include <stdio.h>

int size_shirt(){
printf("\n");

char sizeOfShirt;

do{
printf("What Size of Shirt (S, M, L): ");
scanf(" %c", &sizeOfShirt);
}while(sizeOfShirt != 'S' && sizeOfShirt != 'L' && sizeOfShirt !='L');
}

void main(){
size_shirt();
}