Code

    VV A(5, VI(5));
    // 10x10で確保したくなった
    A.resize(10, VI(10));
    for(auto a : A){
      debug(a);
    }
    exit(0);

Result

[a]: {0, 0, 0, 0, 0}
[a]: {0, 0, 0, 0, 0}
[a]: {0, 0, 0, 0, 0}
[a]: {0, 0, 0, 0, 0}
[a]: {0, 0, 0, 0, 0}
[a]: {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
[a]: {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
[a]: {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
[a]: {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
[a]: {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}