foo.c: In function 'gys':
foo.c:4:8: error: 'a' undeclared (first use in this function)
    4 |  while(a!=b)
      |        ^
foo.c:4:8: note: each undeclared identifier is reported only once for each function it appears in
foo.c:4:11: error: 'b' undeclared (first use in this function)
    4 |  while(a!=b)
      |           ^
foo.c: In function 'main':
foo.c:20:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   20 |  for(x=3;x<=y;x++)
      |  ^~~
foo.c:22:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   22 |   printf("%d\n",sum);
      |   ^~~~~~
foo.c:23:3: error: expected declaration or statement at end of input
   23 |   return 0;
      |   ^~~~~~
foo.c:15:10: warning: unused variable 'z' [-Wunused-variable]
   15 |  int x,y,z,a[100],sum;
      |          ^
foo.c: In function 'gys':
foo.c:12:1: warning: control reaches end of non-void function [-Wreturn-type]
   12 | }
      | ^
foo.c: In function 'main':
foo.c:16:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   16 |  scanf("%d",&y);
      |  ^~~~~~~~~~~~~~
foo.c:18:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   18 |   scanf("%d",&a[x]);
      |   ^~~~~~~~~~~~~~~~~

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