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* &lt; *n*) such that *d*<sub class="lower-index">*x*</sub> = 4 and *d*<sub class="lower-index">*x* + 1</sub> = 7, if *x* is odd, then to assign *d*<sub class="lower-index">*x*</sub> = *d*<sub class="lower-index">*x* + 1</sub> = 4, otherwise to assign *d*<sub class="lower-index">*x*</sub> = *d*<sub class="lower-index">*x* + 1</sub> = 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.
The first line contains two integers *n* and *k* (1 ≤ *n* ≤ 10<sup class="upper-index">5</sup>, 0 ≤ *k* ≤ 10<sup class="upper-index">9</sup>) — 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 *d*<sub class="lower-index">1</sub>. It is guaranteed that the first digit of the number does not equal zero.
7 4
4727447
4427477
4 2
4478
4478
7 7
4211147
4211177
7 6
4747477
4444477
10 2
9474444474
9774444774
10 47
4214777477
4217777777
3 99
447
477
4 1000000000
7747
7744
3 1000000000
447
447
3 100
447
447
7 74
4777774
4777774
10 200
6860544593
6860544593
10 477
5837934237
5837934237
47 7477
83492039276961836565341994102530448486552156001
83492039276961836565341994102530448486552156001
100 0
9179665522184092255095619209953008761499858159751083177424923082479016015954927554823400601862864827
9179665522184092255095619209953008761499858159751083177424923082479016015954927554823400601862864827
485 9554485
77591213686327368525391827531734680282181149581181587323024775516707756080151536104831756264659461447807315739541829004122483827102803764919259852061561098901393332937462039404423475012940096002301663119780442182470831027122573263011092200024968051233448164275142862251531399243063800892848783227559284462449919786387761960941614255036371684927500361571685732032325070607701306810264624073744998990612133986362972207072576588540217974702060321406370425911824802563123926135054749895722
77591213686327368525391827531734680282181149581181587323024475516707756080151536104831756264659461447807315739541829004122483827102803764919259852061561098901393332937462039404423475012940096002301663119780442182470831027122573263011092200024968051233448164275142862251531399243063800892848783227559284462449919786387761960941614255036371684927500361571685732032325070607701306810264624073744998990612133986362972207072576588540217974702060321406370425911824802563123926135054749895722
74 7
47437850490316923506619313479471062875964157742919669484484624083960118773
44437850490316923506619313449771062875964157742919669484484624083960118773
47 7
77774477747474477477477774747747447447774777474
77774777747474477477477774747747447447774777474
100 2
7477774774777474774777777474474474744477777477774444477444774474477774777474774744477474744474777444
7777774474777474774777777474474474744477777477774444477444774474477774777474774744477474744474777444
99 1
474747444774447474444477474747774774447444477744774744477747777474777774777474477744447447447447477
444747444774447474444477474747774774447444477744774744477747777474777774777474477744447447447447477
74 1000000000
77474447774774747474777447474777777477474444477747444777447444474744744444
77444444774774747474777447474777777477474444477747444777447444474744744444
74 999999999
47474777744447477747777774774777447474747747447744474777477474777774774447
44444477744447477747777774774777447474747747447744474777477474777774774447
100 47
4346440647444704624490777777537777677744747437443404484777536674477779371445774947477174444474400267
4346440644444404624490777777537777677747747437443404484777536674477779371445774947477174444474400267
100 1000000000
5849347454478644774747479437170493249634474874684784475734456487776740780444477442497447771444047377
5849377454448644774747479437170493249634474874684784475734456487776740780444477442497447771444047377
154 96
7967779274474413067517474773015431177704444740654941743448963746454006444442746745494233876247994374947948475494434494479684421447774484909784471488747487
7967779274444413067517444773015431177704444740654941743448963746454006444442746745494233876247994374947948475494434494479684421447774484909784471488747487
2 0
47
47
5 0
12473
12473
n, k = map(int, input().split())
t = list(input())
i, m = 0, n // 2
if k > m: k = m + ((m + k) & 1)
while k and i < n - 1:
    if t[i] == '4' and t[i + 1] == '7':
        k -= 1
        if i & 1 == 0: t[i + 1] = '4'
        else:
            t[i] = '7'
            i -= 2
    i += 1
print(''.join(t))

	 	 					  	 	  		 					 	 			