View Compilation Error

0_0_30031499_2883.cpp: In function 'int main()':
0_0_30031499_2883.cpp:125:60: error: 'i' was not declared in this scope
   for(int i = 0 ; i <= Maxn * 4 - 1 ; i++) G[i].clear(); G[i].clear();
                                                            ^