Compilare: main.cpp: In function 'long long int rec(long long int, long long int)': main.cpp:12:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 12 | for(int i=0; i<mat[x][y].size(); i++) | ~^~~~~~~~~~~~~~~~~ main.cpp:11:22: warning: variable 'ok' set but not used [-Wunused-but-set-variable] 11 | int sum=0, nr=0, ok=0; | ^~