View Compilation Error

0_0_33570478_32174.cpp: In function 'int main()':
0_0_33570478_32174.cpp:56:18: error: 'i' was not declared in this scope
          if(date[i].local==date[i-1].local&&date[i].time==date[i-1].time&&date[i].id>date[i-1].id&&used[date[i-1].id]==1)
                  ^