View Compilation Error

0_0_33296107_17717.cpp:44:15: error: conflicting declaration 'std::map<int, int> M'
 map<int, int> M;
               ^
0_0_33296107_17717.cpp:22:11: note: previous declaration as 'const int M'
 const int M = 1e6 + 5;
           ^
0_0_33296107_17717.cpp: In function 'int main()':
0_0_33296107_17717.cpp:72:24: error: invalid types 'const int[int]' for array subscript
     rep(i,1,2*n) M[b[i]] = i;
                        ^
0_0_33296107_17717.cpp:86:26: error: invalid types 'const int[int]' for array subscript
         int pos2 = M[a[i]];
                          ^