foo.c: In function 'main':
foo.c:29:28: warning: unused variable 'y' [-Wunused-variable]
   29 |  int a,b,c,d,fz1,fm1,fz,fm,y;
      |                            ^
foo.c: In function 'gy':
foo.c:12:1: warning: control reaches end of non-void function [-Wreturn-type]
   12 | }
      | ^
foo.c: In function 'gb':
foo.c:26:1: warning: control reaches end of non-void function [-Wreturn-type]
   26 | }
      | ^
foo.c: In function 'main':
foo.c:30:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   30 |  scanf("%d%d%d%d",&a,&b,&c,&d);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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