/in/foo.cc: In function 'int main()':
/in/foo.cc:42:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int j = 0; j < s.size(); j++) {
                    ~~^~~~~~~~~~
/in/foo.cc:49:17: warning: 'p' may be used uninitialized in this function [-Wmaybe-uninitialized]
    v[i]=v[i]+v[i/p];
                ~^~