/in/ex4.cpp: In function 'int main()':
/in/ex4.cpp:10:17: error: ISO C++ forbids variable length array 'matrix' [-Werror=vla]
  int matrix[n][m] = { 0 };
                 ^
/in/ex4.cpp:10:17: error: ISO C++ forbids variable length array 'matrix' [-Werror=vla]
/in/ex4.cpp:10:6: error: unused variable 'matrix' [-Werror=unused-variable]
  int matrix[n][m] = { 0 };
      ^~~~~~
/in/ex4.cpp:10:17: error: 'm' is used uninitialized in this function [-Werror=uninitialized]
  int matrix[n][m] = { 0 };
                 ^
/in/ex4.cpp:10:17: error: 'n' is used uninitialized in this function [-Werror=uninitialized]
cc1plus: all warnings being treated as errors