Buggy python submission (verdict: Time Limit Exceeded):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)


def main():
    rr = []
    M = 256

    def f(m, n):
        cs = [I() for _ in range(m)]
        xs = [I() for _ in range(n)]
        d = [inf] * M
        d[128] = 0
        for i in range(n):
            x = xs[i]
            nd = [inf] * M
            for k in range(M):
                v = d[k]
                for j in range(m):
                    c = cs[j]
                    nk = max(min(k+c,255),0)
                    if nd[nk] > v + pow(x-nk, 2):
                        nd[nk] = v + pow(x-nk, 2)
            d = nd
        return min(d)

    while True:
        n,m = LI()
        if m == 0 and n == 0:
            break
        rr.append(f(m,n))

    return '\n'.join(map(str,rr))




print(main())



Fixed submission:
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)


def main():
    rr = []
    M = 256
    sq = [i**2 for i in range(M)]
    nkss = [[sq[abs(x-nk)] for nk in range(M)] for x in range(M)]
    ML = list(range(M))

    def f(m, n):
        cs = [I() for _ in range(m)]
        xs = [I() for _ in range(n)]
        ml = list(range(m))
        d = [inf] * M
        nd = [inf] * M
        d[128] = 0
        ckl = list(map(lambda x: (max(min(x[0]+x[1], 255), 0), x[1]), (itertools.product(cs, ML))))
        for i in range(n):
            nd = [inf] * M
            for nk,k in ckl:
                if nd[nk] > d[k]:
                    nd[nk] = d[k]
            d = [nn + kk for nn,kk in zip(nd, nkss[xs[i]])]
        return min(d)

    while True:
        n,m = LI()
        if m == 0 and n == 0:
            break
        rr.append(f(m,n))

    return '\n'.join(map(str,rr))




print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)


def main():
    rr = []
    M = 256
    sq = [i**2 for i in range(M)]
    nkss = [[sq[abs(x-nk)] for nk in range(M)] for x in range(M)]
    ML = list(range(M))

    def f(m, n):
        cs = [I() for _ in range(m)]
        xs = [I() for _ in range(n)]
        ml = list(range(m))
        d = [inf] * M
        nd = [inf] * M
        d[128] = 0
        for i in range(n):
            nd = [inf] * M
            nks = nkss[xs[i]]
            for j in ml:
                c = cs[j]
                for k in ML:
                    nk = k+c
                    if nk < 0:
                        nk = 0
                    elif nk > 255:
                        nk = 255
                    if nd[nk] > d[k]:
                        nd[nk] = d[k]
            for nk in ML:
                nd[nk] += nks[nk]
            d = nd
        return min(d)

    while True:
        n,m = LI()
        if m == 0 and n == 0:
            break
        rr.append(f(m,n))

    return '\n'.join(map(str,rr))




print(main())



Fixed submission:
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)


def main():
    rr = []
    M = 256
    sq = [i**2 for i in range(M)]
    nkss = [[sq[abs(x-nk)] for nk in range(M)] for x in range(M)]
    ML = list(range(M))

    def f(m, n):
        cs = [I() for _ in range(m)]
        xs = [I() for _ in range(n)]
        ml = list(range(m))
        d = [inf] * M
        nd = [inf] * M
        d[128] = 0
        ckl = list(map(lambda x: (max(min(x[0]+x[1], 255), 0), x[1]), (itertools.product(cs, ML))))
        for i in range(n):
            nd = [inf] * M
            for nk,k in ckl:
                if nd[nk] > d[k]:
                    nd[nk] = d[k]
            d = [nn + kk for nn,kk in zip(nd, nkss[xs[i]])]
        return min(d)

    while True:
        n,m = LI()
        if m == 0 and n == 0:
            break
        rr.append(f(m,n))

    return '\n'.join(map(str,rr))




print(main())

Buggy python submission (verdict: Runtime Error):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 998244353

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)


def main():
    rr = []

    while True:
        n,m = LI()
        if n == 0 and m == 0:
            break

        cs = [I() for _ in range(m)]
        xs = [I() for _ in range(n)]
        d = collections.defaultdict(int)
        d[128] = 0
        for x in xs:
            n = collections.defaultdict(lambda: inf)
            for k,v in d.items():
                for c in cs:
                    nk = max(min(k+c,255),0)
                    if n[nk] > v + (x-nk) ** 2:
                        n[nk] = v + (x-nk) ** 2
            d = n

        rr.append(min(d.values()))


    return '\n'.join(map(str, rr))


print(main())




Fixed submission:
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)


def main():
    rr = []
    M = 256
    sq = [i**2 for i in range(M)]
    nkss = [[sq[abs(x-nk)] for nk in range(M)] for x in range(M)]
    ML = list(range(M))

    def f(m, n):
        cs = [I() for _ in range(m)]
        xs = [I() for _ in range(n)]
        ml = list(range(m))
        d = [inf] * M
        nd = [inf] * M
        d[128] = 0
        ckl = list(map(lambda x: (max(min(x[0]+x[1], 255), 0), x[1]), (itertools.product(cs, ML))))
        for i in range(n):
            nd = [inf] * M
            for nk,k in ckl:
                if nd[nk] > d[k]:
                    nd[nk] = d[k]
            d = [nn + kk for nn,kk in zip(nd, nkss[xs[i]])]
        return min(d)

    while True:
        n,m = LI()
        if m == 0 and n == 0:
            break
        rr.append(f(m,n))

    return '\n'.join(map(str,rr))




print(main())