/in/ex4.cpp: In function 'int main()':
/in/ex4.cpp:17:26: error: ISO C++ forbids variable length array 'pond' [-Werror=vla]
     vector<int> pond[l][w];
                          ^
/in/ex4.cpp:17:26: error: ISO C++ forbids variable length array 'pond' [-Werror=vla]
/in/ex4.cpp:21:33: error: lvalue required as left operand of assignment
             pond[i] + j = (int) a;
                                 ^
/in/ex4.cpp:27:16: error: expected '(' before 'pond'
             if pond[i][j] == 3
                ^~~~
/in/ex4.cpp:32:13: error: 'idx' was not declared in this scope
     cout << idx << endl;
             ^~~
/in/ex4.cpp:32:13: note: suggested alternative: 'id_t'
     cout << idx << endl;
             ^~~
             id_t
cc1plus: all warnings being treated as errors