/in/foo.c: In function 'main':
/in/foo.c:22:24: warning: '
   ' directive writing 1 byte into a region of size between 0 and 18 [-Wformat-overflow=]
             sprintf(t, "%d:%d\n",w11,l11);
                        ^~~~~~~~~
/in/foo.c:22:13: note: 'sprintf' output between 5 and 23 bytes into a destination of size 21
             sprintf(t, "%d:%d\n",w11,l11);
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.c:28:24: warning: '
   ' directive writing 1 byte into a region of size between 0 and 18 [-Wformat-overflow=]
             sprintf(t, "%d:%d\n",w21,l21);
                        ^~~~~~~~~
/in/foo.c:28:13: note: 'sprintf' output between 5 and 23 bytes into a destination of size 21
             sprintf(t, "%d:%d\n",w21,l21);
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.c:34:16: warning: '
   ' directive writing 1 byte into a region of size between 0 and 18 [-Wformat-overflow=]
     sprintf(t, "%d:%d\n",w11,l11);
                ^~~~~~~~~
/in/foo.c:34:5: note: 'sprintf' output between 5 and 23 bytes into a destination of size 21
     sprintf(t, "%d:%d\n",w11,l11);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.c:36:16: warning: '
   ' directive writing 1 byte into a region of size between 0 and 18 [-Wformat-overflow=]
     sprintf(t, "%d:%d\n",w21,l21);
                ^~~~~~~~~
/in/foo.c:36:5: note: 'sprintf' output between 5 and 23 bytes into a destination of size 21
     sprintf(t, "%d:%d\n",w21,l21);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~