/in/foo.c: In function 'main':
/in/foo.c:8:12: warning: statement with no effect [-Wunused-value]
   a[n]>=100&&a[n]<=120;
   ~~~~~~~~~^~~~~~~~~~~
/in/foo.c:12:11: warning: statement with no effect [-Wunused-value]
     x>=100&&x<=120;
     ~~~~~~^~~~~~~~
/in/foo.c:17:4: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
   c++;
   ~^~