Main.cc: In function 'int main()':
Main.cc:6:15: error: conflicting declaration 'int a [1000]'
int a[1000];
^
Main.cc:5:9: note: previous declaration as 'int a'
int a,b;
^
Main.cc:10:17: error: invalid types 'int[int]' for array subscript
j+=a[i];
^