View Compilation Error

0_0_13601336_14951.cpp: In function 'int main()':
0_0_13601336_14951.cpp:23:8: error: 'i' was not declared in this scope
     po[i][0] = w;
        ^
0_0_13601336_14951.cpp:29:7: error: 'i' was not declared in this scope
    po[i][0] = w - youchang;
       ^
0_0_13601336_14951.cpp:35:7: error: 'i' was not declared in this scope
    po[i][0] = w - youchang;
       ^
0_0_13601336_14951.cpp:38:26: error: 'i' was not declared in this scope
   double shengchang = po[i - 1][0];
                          ^