Compilare: main.cpp: In function 'int main()': main.cpp:26:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 26 | if(left_ < mat[i].size()) { | ~~~~~~^~~~~~~~~~~~~~~ main.cpp:32:22: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 32 | if(mat[i].size() > c) { | ~~~~~~~~~~~~~~^~~