The problem is that %c in the scanf call will read a newline leftover in the input stream from the previous loops read of the integer value. Simplest solution there is to add a space in front of the %c format specifier which will tell the scanf call to ignore leading whitespace.
^ there's a space there now
Avoid casting the return value of the malloc call.
#3 You should be setting the next pointer of the newly allocated node to null after you create it, also you head node's next pointer.
main returns int not void.
If you expect to actually do anything with those head/tail pointers in main after the call to addNode then you'll need to change your addNode function to accept pointer-to-pointer-to-Node arguments rather than just simple pointer-to-Node arguments.
void addNode(Node *head,Node *tail)
Node *head=NULL, *tail=NULL;