Buggy python submission (verdict: Runtime Error):
while 1:
    d, w = map(int, input().split())
    if d==w==0:
        break
    E=[list(map(int, input().split())) for i in range(d)]
    a=0
    for x2 in range(d):
        for y2 in range(w):
            for x1 in range(x2-1):
                for y1 in range(y2-1):
                    co=10**18
                    for x in range(x1, x2+1):
                        co=min(co, E[x][y1], E[x][y2])
                    for y in range(y1, y2+1):
                        co=min(co, E[x1][y], E[x2][y])
                    ci=cnt=0
                    for x in range(x1+1, x2):
                        for y in range(y1+1, y2):
                            ci=max(ci, E[x][y])
                            cnt+=E[x][y]
                    if ci < co:
                        a=max(ans, (x2-x1-1)*(y2-y1-1)*co - cnt)
    print(a)



Fixed submission:
while True:
    d, w = map(int, input().split())
    if d == 0:
        break
    area = []
    for _ in range(d):
        area.append(list(map(int, input().split())))
    a = 0
    for dp in range(1, d - 1):
        for wp in range(1, w - 1):
            for i in range(1, d - dp):
                for j in range(1, w - wp):
                    mawari = min(area[i - 1][j - 1:j + wp + 1] + area[i + dp][j - 1:j + wp + 1])
                    naka = 0
                    for ii in range(dp):
                        mawari = min(mawari, area[i + ii][j - 1], area[i + ii][j + wp])
                        naka = max([naka] + area[i + ii][j:j + wp])
                    if mawari > naka:
                        vn = 0
                        for ii in range(dp):
                            for jj in range(wp):
                                vn += mawari - area[i + ii][j + jj]
                        a = max(vn, a)
    print(a)

Buggy python submission (verdict: Runtime Error):
while 1:
    d, w = map(int, input().split())
    if d==w==0:
        break
    E=[list(map(int, input().split())) for i in range(d)]
    a=0
    for x2 in range(d):
        for y2 in range(w):
            for x1 in range(x2-1):
                for y1 in range(y2-1):
                    co=10**18
                    for x in range(x1, x2+1):
                        co=min(co, E[x][y1], E[x][y2])
                    for y in range(y1, y2+1):
                        co=min(co, E[x1][y], E[x2][y])
                    ci=cnt=0
                    for x in range(x1+1, x2):
                        for y in range(y1+1, y2):
                            ci=max(ci, E[x][y])
                            cnt+=E[x][y]
                    if ci < co:
                        a=max(ans, (x2-x1-1)*(y2-y1-1)*co - cnt)
    print(a)



Fixed submission:
while True:
    d, w = map(int, input().split())
    if d == 0:
        break
    area = []
    for _ in range(d):
        area.append(list(map(int, input().split())))
    a = 0
    for dp in range(1, d - 1):
        for wp in range(1, w - 1):
            for i in range(1, d - dp):
                for j in range(1, w - wp):
                    mawari = min(area[i - 1][j - 1:j + wp + 1] + area[i + dp][j - 1:j + wp + 1])
                    naka = 0
                    for ii in range(dp):
                        mawari = min(mawari, area[i + ii][j - 1], area[i + ii][j + wp])
                        naka = max([naka] + area[i + ii][j:j + wp])
                    if mawari > naka:
                        vn = 0
                        for ii in range(dp):
                            for jj in range(wp):
                                vn += mawari - area[i + ii][j + jj]
                        a = max(vn, a)
    print(a)

Buggy python submission (verdict: Runtime Error):
while True:
    d, w = map(int, input().split())
    if d==w==0:
        break
    E=[list(map(int, input().split())) for i in range(d)]
    a=0
    for x2 in range(d):
        for y2 in range(w):
            for x1 in range(x2-1):
                for y1 in range(y2-1):
                    co=10**18
                    for x in range(x1, x2+1):
                        co=min(co, E[x][y1], E[x][y2])
                    for y in range(y1, y2+1):
                        co=min(co, E[x1][y], E[x2][y])
                    ci=cnt=0
                    for x in range(x1+1, x2):
                        for y in range(y1+1, y2):
                            ci=max(ci, E[x][y])
                            cnt+=E[x][y]
                    if ci < co:
                        a=max(ans, (x2-x1-1)*(y2-y1-1)*co - cnt)
    print(a)



Fixed submission:
while True:
    d, w = map(int, input().split())
    if d == 0:
        break
    area = []
    for _ in range(d):
        area.append(list(map(int, input().split())))
    a = 0
    for dp in range(1, d - 1):
        for wp in range(1, w - 1):
            for i in range(1, d - dp):
                for j in range(1, w - wp):
                    mawari = min(area[i - 1][j - 1:j + wp + 1] + area[i + dp][j - 1:j + wp + 1])
                    naka = 0
                    for ii in range(dp):
                        mawari = min(mawari, area[i + ii][j - 1], area[i + ii][j + wp])
                        naka = max([naka] + area[i + ii][j:j + wp])
                    if mawari > naka:
                        vn = 0
                        for ii in range(dp):
                            for jj in range(wp):
                                vn += mawari - area[i + ii][j + jj]
                        a = max(vn, a)
    print(a)