/in/foo.cc: In function 'int main()':
/in/foo.cc:7:3: error: expected initializer before 'cin'
   cin>>n;
   ^~~
/in/foo.cc:10:3: error: 'a' was not declared in this scope
   a[i][i]=1;
   ^
/in/foo.cc:15:4: error: 'a' was not declared in this scope
    a[i][j]=a[i-1][j]+a[i-1][j-1];
    ^
/in/foo.cc:19:10: error: 'a' was not declared in this scope
    cout<<a[i][j];
          ^
/in/foo.cc:22:2: error: expected '}' at end of input
  }
  ^