Petya loves lucky numbers. Everybody knows that lucky numbers are positive integers whose decimal representation contains only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not. Petya has a number consisting of n digits without leading zeroes. He represented it as an array of digits without leading zeroes. Let's call it d . The numeration starts with 1, starting from the most significant digit. Petya wants to perform the following operation k times: find the minimum x (1 ≤ x n) such that d x = 4 and d x + 1 = 7, if x is odd, then to assign d x = d x + 1 = 4, otherwise to assign d x = d x + 1 = 7. Note that if no x was found, then the operation counts as completed and the array doesn't change at all. You are given the initial number as an array of digits and the number k . Help Petya find the result of completing k operations.

输入描述:

The first line contains two integers n and k(1 ≤ n ≤ 105, 0 ≤ k ≤ 109) — the number of digits in the number and the number of completed operations. The second line contains n digits without spaces representing the array of digits d, starting with d1. It is guaranteed that the first digit of the number does not equal zero.

输出描述:

In the single line print the result without spaces — the number after the k operations are fulfilled.

备注:

In the first sample the number changes in the following sequence: 4727447 → 4427447 → 4427477 → 4427447 → 4427477.In the second sample: 4478 → 4778 → 4478.