0(1) element: null
1(2) element: PyImportStatement
2(3) WRITE ACCESS: sys
3(4) element: PyTryExceptStatement
4(5,11) element: PyTryPart
5(6,11) element: PyAssignmentStatement
6(7,11) READ ACCESS: int
7(8,11) element: PySubscriptionExpression
8(9,11) READ ACCESS: sys
9(10,11) element: PyCallExpression: int
10(11,17) WRITE ACCESS: n
11(12) element: PyExceptPart
12(13) READ ACCESS: ValueError
13(14) element: PyPrintStatement
14(15) element: PyExpressionStatement
15(16) READ ACCESS: sys
16(17) element: PyCallExpression: sys.exit
17(18) element: PyPrintStatement
18(19) READ ACCESS: str
19(20) READ ACCESS: n
20(21) element: PyCallExpression: str
21() element: null