Local variable is not initialized in C++

ex1.cpp

#include <iostream>

int fn() {
    int x;
    return x;   // returns uninitialized local variable
}

int main(int argc, char*args[]) {
    //std::cout << "Hello\n";
    std::cout << fn() << "\n";
    std::cout << fn() << "\n";
}

/****

$ g++ ex1.cpp && ./a.out
0
32767       <-- !!!!!!!

$ g++ --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.3.0
Thread model: posix

 ****/