import copy
N,K = map(int,input().split())
S = list(input())
ans = []
for i in range(N-K+1):
    ans.append(S[i+K-1])
if (N+K) % 2 == 0:
    ans += reversed(S[:K-1])
else:
    ans += S[:K-1]
print(*ans,sep='')