Compilare: main.cpp: In function 'void f(int)': main.cpp:20:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | for (int j=0;j<v[i].size();j++) | ~^~~~~~~~~~~~ main.cpp:13:9: warning: unused variable 'st' [-Wunused-variable] 13 | int st=1,dr=1; | ^~ main.cpp:13:14: warning: unused variable 'dr' [-Wunused-variable] 13 | int st=1,dr=1; | ^~