$ cargo run Compiling collections v0.1.0 (file:///projects/collections) Finished dev [unoptimized + debuginfo] target(s) in 0.43s Running `target/debug/collections` thread 'main' panicked at 'byte index 1 is not a char boundary; it is inside 'З' (bytes 0..2) of `Здравствуйте`', src/main.rs:4:14 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace