Main.cc: In function 'int main()':
Main.cc:6:8: error: 'n' was not declared in this scope
int a[n];
^
Main.cc:8:10: error: 'a' was not declared in this scope
cin >> a[i];
^
Main.cc:12:2: error: 'a' was not declared in this scope
a[b - 1] = c;
^