interval.cpp: In function 'int main()':
interval.cpp:35:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   35 |  for(int i=1;i<a.size();i++){
      |              ~^~~~~~~~~
interval.cpp:41:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |  for(int i=1;i<b.size();i++){
      |              ~^~~~~~~~~
interval.cpp:46:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |  for(int i=1;i<a.size();i++){
      |              ~^~~~~~~~~
interval.cpp:53:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   53 |  for(int i=1;i<b.size();i++){
      |              ~^~~~~~~~~