foo.c: In function 'main':
foo.c:4:36: warning: variable 'j' set but not used [-Wunused-but-set-variable]
    4 |  int a1,a2,b1,b2,num1,num2,m,n,r,k,j;
      |                                    ^
foo.c:5:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    5 |  scanf("%d%d",&b1,&a1);
      |  ^~~~~~~~~~~~~~~~~~~~~
foo.c:6:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    6 |  scanf("%d%d",&b2,&a2);
      |  ^~~~~~~~~~~~~~~~~~~~~

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