657 B | 657 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from datetime import datetime, timedelta
BLANK = " "
#inp = input
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
n, k = mii()
l = input().split()
crt = len(l[0])
s = l[0]
for i in l[1:]:
if crt + len(i) <= k:
crt += len(i)
s += " " + i
else:
p(s)
crt = len(i)
s = i
p(s)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()