/in/foo.cc: In function 'int main()':
/in/foo.cc:12:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(int i = 1;i <= a.length();i++)
               ~~^~~~~~~~~~~~~
/in/foo.cc:13:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(int j = 1;j <= b.length();j++)
               ~~^~~~~~~~~~~~~
/in/foo.cc:18:47: error: expected '}' at end of input
 cout << a.length() - f[a.length()][a.length()];
                                               ^