Main.cpp: In function 'bool is_valid(std::string)':
Main.cpp:11:19: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
11 | for(register int i = 0; i < (int)s.size(); ++i){
| ^
Main.cpp: In lambda function:
Main.cpp:32:20: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
32 | for(register int i = 1; i <= n; ++i){
| ^
Main.cpp:43:20: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
43 | for(register int i = 1; i <= n*2; ++i){
| ^
Main.cpp:49:21: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
49 | for(register int i = 1; i <= n; ++i) cout << ans[i] << ' ';
| ^