std::chrono::year::max - cppreference.com

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static constexpr year max() noexcept;		(since C++20)

Returns the largest possible year, that is, std::chrono::year(32767).

std::chrono::year(32767)

Run this code

#include <chrono>
#include <iostream>

int main()
{
    std::cout << "The maximum year is: " << (int)std::chrono::year::max() << '\n';
}

Output:

The maximum year is: 32767