View Compilation Error

0_0_17838306_13693.cpp: In function 'int main()':
0_0_17838306_13693.cpp:5:66: error: 'i' was not declared in this scope
     for(int i=1;i<=T;++i) scanf("%d",&x);printf("Case #%d: %d\n",i,a[x]);
                                                                  ^