/in/foo.cc: In function 'int main()':
/in/foo.cc:24:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while(pq1.size()>(i+1)/2){
          ~~~~~~~~~~^~~~~~~~
/in/foo.cc:29:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while(pq2.size()>i/2){
          ~~~~~~~~~~^~~~