/in/foo.cc: In function 'void xzpx()':
/in/foo.cc:11:16: error: 'i' was not declared in this scope
   11 |         swap(z[i],z[j]);
      |                ^
/in/foo.cc:11:21: error: 'j' was not declared in this scope
   11 |         swap(z[i],z[j]);
      |                     ^