/in/foo.cc: In function 'int main()':
/in/foo.cc:9:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<t.size();i++)
              ~^~~~~~~~~
/in/foo.cc:11:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<s.size();j++) if(s[j]==t[i]) a[j]=1;
               ~^~~~~~~~~
/in/foo.cc:13:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s.size();i++) if(a[i]==0) cout<<s[i];
              ~^~~~~~~~~