/in/foo.cc: In function 'int main()':
/in/foo.cc:7:2: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
  if(b==4 || b==6 || b==9 || b==11)
  ^~
/in/foo.cc:9:3: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
   if(b==2)
   ^~
/in/foo.cc:10:14: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    if(a%4==0 && a%100!=0 || a%400==0)
       ~~~~~~~^~~~~~~~~~~
/in/foo.cc:9:5: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
   if(b==2)
     ^