/in/foo.cc: In function 'int main()':
/in/foo.cc:25:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(j=0;j<t.length();j++)
            ~^~~~~~~~~~~
/in/foo.cc:41:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(j=0;j<a.length();j++)
            ~^~~~~~~~~~~