Compilare: main.cpp: In function 'void add(int)': main.cpp:20:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | if (j < nr[i].size()) | ~~^~~~~~~~~~~~~~ main.cpp: In function 'void substract(int)': main.cpp:40:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 40 | if (j < nr[i].size()) | ~~^~~~~~~~~~~~~~