这个向量输出哪里错误了

#include
#include
using namespace std;
struct QUA
{
int x;
int y;
};
class block
{
public: vector c1;
public: vector c2;
};
vector b;
int main()
{
QUA q;
q.x=1;
q.y=2;
b[0].c1.push_back(q);
cout<<b[0].c1[0].x<<" "<<b[0].c1[0].y<<endl;

return 0;

}