/in/foo.c: In function 'prime':
/in/foo.c:72:2: warning: this 'else' clause does not guard... [-Wmisleading-indentation]
  else
  ^~~~
/in/foo.c:81:3: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'else'
   if(k==0)
   ^~