View Compilation Error

0_0_35852149_24629.cpp: In function 'int main()':
0_0_35852149_24629.cpp:10:4: error: 'ans' was not declared in this scope
    ans+=a;
    ^
0_0_35852149_24629.cpp:12:9: error: 'ans' was not declared in this scope
   cout<<ans<<endl<<endl;
         ^