foo.c: In function 'main':
foo.c:11:13: warning: suggest parentheses around comparison in operand of '&' [-Wparentheses]
   11 |         if(i<1000&i>=100)
      |            ~^~~~~
foo.c:17:9: warning: 'c' may be used uninitialized [-Wmaybe-uninitialized]
   17 |         switch(c)
      |         ^~~~~~
foo.c:4:17: note: 'c' was declared here
    4 |         int a,b,c,i,m=0;
      |                 ^

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