cnscan
int cnscan(void);
if ((c = cnscan()) != -1)
int cnscan(void);
if ((c = cnscan()) != -1)
if ((c = cnscan()) == -1) {
int cnscan(void);
int cnscan(void);
if ((c = cnscan()) != -1)
int cnscan(void);
if ((c = cnscan()) != -1)
int cnscan(void);
if ((c = cnscan()) != -1)
int cnscan(void);