Compilare: main.cpp: In function 'void solve()': main.cpp:54:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 54 | for(int i=0;i<used.size()-1 and valid;++i) | ~^~~~~~~~~~~~~~ main.cpp:55:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 55 | for(int j=i+1;j<used.size() and valid;++j) | ~^~~~~~~~~~~~ main.cpp:69:22: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 69 | if(cate[2].size()==n) | ~~~~~~~~~~~~~~^~~ main.cpp: In function 'int main()': main.cpp:196:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 196 | for(int i=1;i<pr.size()-1;++i) | ~^~~~~~~~~~~~ main.cpp:204:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 204 | for(int i=1;i<pr.size()-1;++i) | ~^~~~~~~~~~~~ main.cpp:214:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 214 | for(int i=1;i<pr.size()-1;++i) | ~^~~~~~~~~~~~ main.cpp:223:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 223 | for(int i=2;i<pr.size()-2;++i) | ~^~~~~~~~~~~~