/in/foo.cc: In function 'void build_t(long long int)':
/in/foo.cc:41:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
     ls.l=fa.l, ls.r=fa.l+fa.r>>1;
                     ~~~~^~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:98:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(R II j=0;j<wei[i].size();j++) _tot+=w[who[i][j]];
                ~^~~~~~~~~~~~~~
/in/foo.cc:111:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(R II k=0;k<wei[j].size();k++) {
                          ~^~~~~~~~~~~~~~