AT_arc191_a [ARC191A] Replace Digits

You are given a string $ S $ of length $ N $ and a string $ T $ of length $ M $ , both consisting of digits from `1` to `9`. You will perform the following operation for $ k=1,2,\ldots,M $ in order: - Choose an integer $ i $ such that $ 1 \le i \le N $ . Then, replace the $ i $ -th character of $ S $ with the $ k $ -th character of $ T $ . Find the maximum possible value of the resulting string $ S $ interpreted as an integer after performing the $ M $ operations.

The input is given from Standard Input in the following format: > $ N $ $ M $ $ S $ $ T $

Print the maximum possible value of the resulting string $ S $ interpreted as an integer after performing the $ M $ operations.

### Sample Explanation 1 The following sequence of operations is optimal: - For $ k=1 $ : Choose $ i=3 $ . Then, $ S = $ `193`. - For $ k=2 $ : Choose $ i=1 $ . Then, $ S = $ `293`. - For $ k=3 $ : Choose $ i=1 $ . Then, $ S = $ `593`. In this case, the value of $ S $ interpreted as an integer is $ 593 $ , which is the maximum. ### Constraints - $ 1 \le N,M \le 10^6 $ - $ N $ and $ M $ are integers. - $ S $ is a string of length $ N $ consisting of digits from `1` through `9`. - $ T $ is a string of length $ M $ consisting of digits from `1` through `9`.