foo.c: In function 'main':
foo.c:23:1: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%d%d",&n1,&n2);
 ^~~~~~~~~~~~~~~~~~~~~
foo.c:24:18: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
 for(i=0;i<n1;i++)scanf("%d",&a1[i]);
                  ^~~~~~~~~~~~~~~~~~
foo.c:25:18: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
 for(i=0;i<n2;i++)scanf("%d",&a2[i]);
                  ^~~~~~~~~~~~~~~~~~

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