View Compilation Error

0_0_33875813_3496.cpp: In function 'int main()':
0_0_33875813_3496.cpp:15:9: error: 'a' was not declared in this scope
    cin>>a[i];
         ^
0_0_33875813_3496.cpp:21:12: error: 'a' was not declared in this scope
        if((a[i+1]-a[i]-1)*d>e){
            ^