vector of vectors

[rossb]

I am terrible with creating "matrices" and was hoping someone would help. How would I make this vector of vector?
30 30 30 30 30
30 20 20 20 30
30 20 10 20 30
30 20 20 20 30
30 30 30 30 30

Thank you for any help!

[JLBorges]

std::vector< std::vector<int> > matrix =
{
    { 30, 30, 30, 30, 30 },
    { 30, 20, 20, 20, 30 },
    { 30, 20, 10, 20, 30 },
    { 30, 20, 20, 20, 30 },
    { 30, 30, 30, 30, 30 }
};