/in/foo.cc:9:23: warning: missing terminating ' character
 a[x-1][y+2]=a[x][y+3]='\';
                       ^
/in/foo.cc:9:23: error: missing terminating ' character
 a[x-1][y+2]=a[x][y+3]='\';
                       ^~~~
/in/foo.cc: In function 'void make(int, int, int)':
/in/foo.cc:15:17: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
 make(n-1,x-(1<<n-1),y+(1<<(n-1)));
                ~^~