Compilare: main.cpp: In function 'int main()': main.cpp:21:44: warning: comparison of integer expressions of different signedness: 'std::stack<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 21 | if(s.top() == '(' and s.size() < n - i) { | ~~~~~~~~~^~~~~~~ main.cpp:30:44: warning: comparison of integer expressions of different signedness: 'std::stack<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 30 | if(s.top() == '[' and s.size() < n - i) { | ~~~~~~~~~^~~~~~~ main.cpp:39:44: warning: comparison of integer expressions of different signedness: 'std::stack<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 39 | if(s.top() == '{' and s.size() < n - i) { | ~~~~~~~~~^~~~~~~