Compilare: main.cpp: In function 'bool ok(int)': main.cpp:40:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 40 | for (i = 0; i < a[x].size(); i++) | ~~^~~~~~~~~~~~~ main.cpp: In function 'void solve()': main.cpp:79:9: warning: unused variable 'i' [-Wunused-variable] 79 | int i; | ^