View Compilation Error

0_0_33025187_29004.cpp: In function 'int main()':
0_0_33025187_29004.cpp:15:3: error: 'a' was not declared in this scope
   a[i][i]=1;
   ^
0_0_33025187_29004.cpp:24:17: error: 'arr' was not declared in this scope
   printf("%d\n",arr[n+1][m+1]);
                 ^