/in/ex3.cpp:10:27: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
    int arr1[500][500] = {0}, arr2[500][500] = {0}, temp[25000] = {0}, num = 0, size = 0;
                          ^
                          {}
/in/ex3.cpp:10:49: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
    int arr1[500][500] = {0}, arr2[500][500] = {0}, temp[25000] = {0}, num = 0, size = 0;
                                                ^
                                                {}
/in/ex3.cpp:15:15: error: implicit conversion turns floating-point number into integer: 'typename __gnu_cxx::__enable_if<__is_integer<int>::__value, double>::__type' (aka 'double') to 'int' [-Werror,-Wfloat-conversion]
    int len = sqrt(size/2);
        ~~~   ^~~~~~~~~~~~
3 errors generated.