transfer.cpp: In function 'vi get_attachment(vi)':
transfer.cpp:8:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
8 | for(int i = 0; i < sz(v); i++) if(v[i]) x^=i+1;
| ^
transfer.cpp: In function 'vi retrieve(vi)':
transfer.cpp:17:2: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
17 | if(v.back()==y and x!=xx) v[(x^xx)-1]^=1; return v;
| ^~
transfer.cpp:17:44: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
17 | if(v.back()==y and x!=xx) v[(x^xx)-1]^=1; return v;
| ^~~~~~