queue_at_the_school.py

"""
If a boy comes just before a girl, then swap all such pairs in the string at each second of time.
"""

n, t = map(int, input().split())
s = list(input())

for _ in range(t):
    i = 0
    while i < n-1:
        if s[i] == 'B' and s[i+1] == 'G':
            s[i], s[i+1] = s[i+1], s[i]
            i += 2
        else:
            i += 1

print(''.join(s))