foo.cc: In function 'int main()':
foo.cc:7:9: error: 'i' was not declared in this scope
    7 |     for(i=x,k=0;i<=y;i++,k++)
      |         ^
foo.cc:7:13: error: 'k' was not declared in this scope
    7 |     for(i=x,k=0;i<=y;i++,k++)
      |             ^
foo.cc:12:9: error: 'i' was not declared in this scope
   12 |     for(i=0;i<k;i++)
      |         ^
foo.cc:12:15: error: 'k' was not declared in this scope
   12 |     for(i=0;i<k;i++)
      |               ^
foo.cc:21:14: error: 'k' was not declared in this scope
   21 |     sort(b,b+k);
      |              ^
foo.cc:22:7: error: 'i' was not declared in this scope
   22 |   for(i=0;i<k;i++)
      |       ^
foo.cc:25:9: error: 'bt' was not declared in this scope; did you mean 'b'?
   25 |         bt=b[i];
      |         ^~
      |         b
foo.cc:26:15: error: 'c' was not declared in this scope
   26 |         while(c)
      |               ^
foo.cc:32:9: error: 'i' was not declared in this scope
   32 |     for(i=0;i<k;i++)
      |         ^

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