Compilare: main.cpp: In function 'int main()': main.cpp:67:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 67 | for(int j=0;j<lines.size();j++) | ~^~~~~~~~~~~~~ main.cpp:86:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 86 | for(int j=0;j<col.size();j++) | ~^~~~~~~~~~~