interval.cpp: In function 'int main()':
interval.cpp:40:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |  for(int i=1;i<a.size();i++){
      |              ~^~~~~~~~~
interval.cpp:48:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |  for(int i=1;i<b.size();i++){
      |              ~^~~~~~~~~
interval.cpp:55:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   55 |  for(int i=1;i<a.size();i++){
      |              ~^~~~~~~~~
interval.cpp:62:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |  for(int i=1;i<b.size();i++){
      |              ~^~~~~~~~~