Runtime Error
/in/foo.cc: In function 'int main()':
/in/foo.cc:11:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(i=0;i<=a.length();i++)
~^~~~~~~~~~~~
/in/foo.cc:36:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(i=0;i<=c.length();i++)
~^~~~~~~~~~~~
