Spreadsheet Formula Evaluator

Implement SET label expression and GET label. An expression consists only of non-negative integers and cell labels joined by plus signs. A SET that would create a dependency cycle is rejected and the old value is kept; GET returns ERROR for a cell that is unset or whose reference chain cannot be evaluated.

输入格式

Each line contains one command; there are at most 1000 commands and at most 300 distinct labels. A label is an uppercase letter followed by digits; an addition expression has at most 50 terms, literals are ≤10^9, and every evaluable result is guaranteed to fit in a signed 64-bit integer. Referencing an unset cell does not form a cycle; GET returns ERROR in that case.

输出格式

For each command, output OK, ERROR or an integer.

样例 1

输入：

SET A1 7
GET A1

输出：

OK
7

样例 2

输入：

SET A1 B1
GET A1
SET B1 4
GET A1

输出：

OK
ERROR
OK
4

样例 3

输入：

SET A1 B1
SET B1 A1
GET A1

输出：

OK
ERROR
ERROR