View Compilation Error

0_0_13928316_27931.cpp: In function 'int main()':
0_0_13928316_27931.cpp:21:10: error: 'i' was not declared in this scope
     for( i=2;i<=n;i++)
          ^
0_0_13928316_27931.cpp:25:11: error: 'i' was not declared in this scope
      for( i=1;i<=n;i++)
           ^
0_0_13928316_27931.cpp:29:11: error: 'i' was not declared in this scope
      for( i=n;i>=1;i--)
           ^