#include <iostream>
#include <vector>
int main(){
std::vector<std::vector<int>> vec = {{0,1},{2,3}};
vec.push_back({4,5});
vec.push_back({5,6});
for (auto &vec2 : vec){
for (auto value : vec2){
std::cout << value << std::endl;
}
}
return 0;
}
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