foo.cc: In function 'int main()':
foo.cc:23:18: error: cannot bind non-const lvalue reference of type 'int&' to a value of type 'long long int'
   23 |     for (int &i: a) {
      |                  ^
foo.cc:23:15: warning: loop variable 'i' of type 'int&' binds to a temporary constructed from type 'long long int' [-Wrange-loop-construct]
   23 |     for (int &i: a) {
      |               ^
foo.cc:23:15: note: use non-reference type 'int' to make the copy explicit or 'const long long int&' to prevent copying

[Hydro](https://hydro.ac)提供评测服务