/in/ex4.cpp: In function 'int main()':
/in/ex4.cpp:10:19: error: ISO C++ forbids variable length array 'pond' [-Werror=vla]
     char pond[m][n];
                   ^
/in/ex4.cpp:10:19: error: ISO C++ forbids variable length array 'pond' [-Werror=vla]
/in/ex4.cpp:22:31: error: too few arguments to function 'int atoi(const char*)'
             pond[i][k] = atoi();
                               ^
In file included from /usr/include/c++/7/cstdlib:75:0,
                 from /usr/include/c++/7/ext/string_conversions.h:41,
                 from /usr/include/c++/7/bits/basic_string.h:6361,
                 from /usr/include/c++/7/string:52,
                 from /usr/include/c++/7/bits/locale_classes.h:40,
                 from /usr/include/c++/7/bits/ios_base.h:41,
                 from /usr/include/c++/7/ios:42,
                 from /usr/include/c++/7/ostream:38,
                 from /usr/include/c++/7/iostream:39,
                 from /in/ex4.cpp:1:
/usr/include/stdlib.h:104:12: note: declared here
 extern int atoi (const char *__nptr)
            ^~~~
cc1plus: all warnings being treated as errors