/in/foo.cc:28:18: error: empty character constant
 if(ch[node][S[i]-'']){
                  ^~
/in/foo.cc:29:20: error: empty character constant
 node=ch[node][S[i]-''];
                    ^~
/in/foo.cc: In function 'int main()':
/in/foo.cc:162:37: warning: operation on 'cntQ' may be undefined [-Wsequence-point]
 scanf("%d%d",&Query[cntQ][0],&Query[++cntQ][1]);
                                     ^~~~~~