Compilare: main.cpp: In function 'void solution()': main.cpp:31:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 31 | for(int i = 0; i < nx.size(); ++ i) | ~~^~~~~~~~~~~ main.cpp:36:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 36 | for(int i = 1; i < nx.size(); ++i) | ~~^~~~~~~~~~~ main.cpp:38:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 38 | for(int j = 1; j < ny.size(); ++ j) | ~~^~~~~~~~~~~