Buggy python submission (verdict: Time Limit Exceeded):
import heapq
n, k = map(int, input().split())
a = list(map(int, input().split()))
f = list(map(int, input().split()))
a.sort(reverse=True)
f.sort()
m = []
for i, j in zip(a, f):
    heapq.heappush(m, (-i*j, i, j))
for i in range(k):
    t = heapq.heappop(m)
    heapq.heappush(m, (-(t[1] - 1)*t[2], t[1]-1, t[2]))
    if m[0][0]== 0:
        print(0)
        break
else:
    print(-m[0][0])



Fixed submission:
import math
def main():
    n, k = map(int, input().split())
    a = list(map(int, input().split()))
    f = list(map(int, input().split()))
    a.sort(reverse=True)
    f.sort()
    hi = a[0] * f[-1]
    lo = 0
    def caneat(m):
        t = 0
        for i, j in zip(a, f):
            if i * j > m:
                t += math.ceil((i*j - m)/j)
            if t > k:
                return False
        return True
    while hi != lo:
        m = (hi + lo) // 2
        if caneat(m):
            hi = m
        else:
            lo = m + 1
    return hi
print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import heapq
n, k = map(int, input().split())
a = list(map(int, input().split()))
f = list(map(int, input().split()))
a.sort(reverse=True)
f.sort()
m = []
for i, j in zip(a, f):
    heapq.heappush(m, (-i*j, i, j))
for i in range(k):
    t = heapq.heappop(m)
    heapq.heappush(m, (-(t[1] - 1)*t[2], t[1]-1, t[2]))
    if min(m, key=lambda x:x[0]) == 0:
        print(0)
        break
else:
    print(-min(m, key=lambda x:x[0])[0])



Fixed submission:
import math
def main():
    n, k = map(int, input().split())
    a = list(map(int, input().split()))
    f = list(map(int, input().split()))
    a.sort(reverse=True)
    f.sort()
    hi = a[0] * f[-1]
    lo = 0
    def caneat(m):
        t = 0
        for i, j in zip(a, f):
            if i * j > m:
                t += math.ceil((i*j - m)/j)
            if t > k:
                return False
        return True
    while hi != lo:
        m = (hi + lo) // 2
        if caneat(m):
            hi = m
        else:
            lo = m + 1
    return hi
print(main())

Buggy python submission (verdict: Time Limit Exceeded):
n, k = map(int, input().split())
a = list(map(int, input().split()))
f = list(map(int, input().split()))
a.sort(reverse=True)
f.sort()
m = [i * j for i, j in zip(a, f)]
for i in range(k):
    t = max(m)
    if t <= 0:
        print(0)
        break
    l = m.index(t)
    a[l] -= 1
    m[l] = a[l] * f[l]
else:
    print(max(m))



Fixed submission:
import math
def main():
    n, k = map(int, input().split())
    a = list(map(int, input().split()))
    f = list(map(int, input().split()))
    a.sort(reverse=True)
    f.sort()
    hi = a[0] * f[-1]
    lo = 0
    def caneat(m):
        t = 0
        for i, j in zip(a, f):
            if i * j > m:
                t += math.ceil((i*j - m)/j)
            if t > k:
                return False
        return True
    while hi != lo:
        m = (hi + lo) // 2
        if caneat(m):
            hi = m
        else:
            lo = m + 1
    return hi
print(main())

Buggy python submission (verdict: Time Limit Exceeded):
n, k = map(int, input().split())
a = list(map(int, input().split()))
f = list(map(int, input().split()))
a.sort(reverse=True)
f.sort()
m = [i * j for i, j in zip(a, f)]
for i in range(k):
    l = m.index(max(m))
    a[l] -= 1
    m[l] = a[l] * f[l]
    if max(m) <= 0:
        print(0)
        break
else:
    print(max(m))



Fixed submission:
import math
def main():
    n, k = map(int, input().split())
    a = list(map(int, input().split()))
    f = list(map(int, input().split()))
    a.sort(reverse=True)
    f.sort()
    hi = a[0] * f[-1]
    lo = 0
    def caneat(m):
        t = 0
        for i, j in zip(a, f):
            if i * j > m:
                t += math.ceil((i*j - m)/j)
            if t > k:
                return False
        return True
    while hi != lo:
        m = (hi + lo) // 2
        if caneat(m):
            hi = m
        else:
            lo = m + 1
    return hi
print(main())