foo.c: In function 'main':
foo.c:6:10: warning: format '%d' expects argument of type 'int *', but argument 2 has type 'int' [-Wformat=]
  scanf("%d",n);
         ~^
foo.c:7:9: warning: right-hand operand of comma expression has no effect [-Wunused-value]
  for(a=1,a<=n,a++)
         ^
foo.c:7:18: error: expected ';' before ')' token
  for(a=1,a<=n,a++)
                  ^
foo.c:7:18: error: expected expression before ')' token
foo.c:6:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",n);
  ^~~~~~~~~~~~~

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