C++ Temporary Proxy Generator Script

I need a small C++ utility that, when invoked from the command line, instantly prints or writes a fresh list of working proxies according to three parameters:

proxy.cpp generate -n <count> -l <countryCode> -o <outputPath>

-n defines how many proxies to issue, ‑l picks the target country (ISO-2 such as US, FR, SG, etc.), and ‑o is an absolute path where the list should be saved as plain text, one proxy per line.

Key behaviour
• Every proxy you output must work over HTTP, HTTPS and SOCKS5 without requiring any form of authentication.
• A generated endpoint stays alive for roughly one hour; after that it may be considered expired and can safely be discarded.
• The program should return quickly even for very large counts (I will sometimes request up to 1 000 000 000).
• Country codes that are not available should raise a clear error message rather than silently falling back to another location.

Deliverables
1. Well-commented C++ source (C++17 or newer) plus any build script or CMake file required to compile it on Windows and Linux.
2. A brief README that documents all parameters, shows an example session, and clarifies how the one-hour validity is achieved or enforced.
3. A sample run that produces at least 100 US proxies and demonstrates that they accept HTTP, HTTPS and SOCKS5 traffic.

I am interested in a clean, dependency-light solution: if you rely on a third-party service or API to obtain the proxy endpoints, mention it in your bid so I can approve it first.