foo.c: In function 'unique':
foo.c:26:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
foo.c: In function 'main':
foo.c:56:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d",&n1,&n2,&n3);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.c:59:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d",&a1[i]);
         ^~~~~~~~~~~~~~~~~~
foo.c:64:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d",&a2[i]);
         ^~~~~~~~~~~~~~~~~~
foo.c:69:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d",&a3[i]);
         ^~~~~~~~~~~~~~~~~~

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