View Compilation Error

0_0_32128688_5454.cpp: In function 'lint det(std::vector<std::vector<long long int> >, int, int)':
0_0_32128688_5454.cpp:31:7: error: 'i' was not declared in this scope
  for (i = 0; i < n; i++) for (j = 0; j < n; j++) a[i][j] %= MOD;
       ^
0_0_32128688_5454.cpp:31:31: error: 'j' was not declared in this scope
  for (i = 0; i < n; i++) for (j = 0; j < n; j++) a[i][j] %= MOD;
                               ^
0_0_32128688_5454.cpp:31:61: error: 'MOD' was not declared in this scope
  for (i = 0; i < n; i++) for (j = 0; j < n; j++) a[i][j] %= MOD;
                                                             ^