foo.c: In function 'main':
foo.c:15:17: warning: this 'else' clause does not guard... [-Wmisleading-indentation]
   15 |                 else
      |                 ^~~~
foo.c:17:25: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
   17 |                         while(a<=n-3)
      |                         ^~~~~

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