Buggy python submission (verdict: Runtime Error):
H,W = map(int,input().split())
A = [list(map(int,input().split())) for _ in [0]*H]
B = [list(map(int,input().split())) for _ in [0]*H]


C = [[abs(b-a) for a,b in zip(a_row,b_row)] for a_row,b_row in zip(A,B)]

dm = [[0]*W for _ in [0]*H]
dm[-1][-1] = 80
for i in range(H-1,-1,-1):
    for j in range(W-1,-1,-1):
        c = C[i][j]
        if i-1>0:
            dm[i-1][j] = max(dm[i-1][j],dm[i][j] + c)
        if j-1>0:
            dm[i][j-1] = max(dm[i-1][j],dm[i][j] + c)

d = [[set() for _ in [0]*W] for _ in [0]*H]
d[0][0] = {C[0][0]}

for i in range(H):
    for j in range(W):
        for n in d[i][j]:
            if i+1<H:
                c = C[i+1][j]
                if n+c <= dm[i][j]:
                    d[i+1][j].add(n+c)
                if n-c <= dm[i][j]:
                    d[i+1][j].add(abs(n-c))
            if j+1<W:
                c = C[i][j+1]
                if n+c <= dm[i][j]:
                    d[i][j+1].add(n+c)
                if n-c <= dm[i][j]:
                    d[i][j+1].add(abs(n-c))
ans = min(abs(o) for o in d[-1][-1])
print(ans)

Fixed submission:
H,W = map(int,input().split())
A = [list(map(int,input().split())) for _ in [0]*H]
B = [list(map(int,input().split())) for _ in [0]*H]


C = [[abs(b-a) for a,b in zip(a_row,b_row)] for a_row,b_row in zip(A,B)]

dm = [[0]*W for _ in [0]*H]
dm[-1][-1] = 80
for i in range(H-1,-1,-1):
    for j in range(W-1,-1,-1):
        c = C[i][j]
        if i-1>=0:
            dm[i-1][j] = max(dm[i-1][j],dm[i][j] + c)
        if j-1>=0:
            dm[i][j-1] = max(dm[i][j-1],dm[i][j] + c)

d = [[set() for _ in [0]*W] for _ in [0]*H]
d[0][0] = {C[0][0]}

for i in range(H):
    for j in range(W):
        for n in d[i][j]:
            if i+1<H:
                c = C[i+1][j]
                if n+c <= dm[i][j]:
                    d[i+1][j].add(n+c)
                if n-c <= dm[i][j]:
                    d[i+1][j].add(abs(n-c))
            if j+1<W:
                c = C[i][j+1]
                if n+c <= dm[i][j]:
                    d[i][j+1].add(n+c)
                if n-c <= dm[i][j]:
                    d[i][j+1].add(abs(n-c))
ans = min(abs(o) for o in d[-1][-1])
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
H,W = map(int,input().split())
A = [list(map(int,input().split())) for _ in [0]*H]
B = [list(map(int,input().split())) for _ in [0]*H]


C = [[abs(b-a) for a,b in zip(a_row,b_row)] for a_row,b_row in zip(A,B)]

d = [[set() for _ in [0]*W] for _ in [0]*H]
d[0][0] = {C[0][0]}

for i in range(H):
    for j in range(W):
        for n in d[i][j]:
            if i+1<H:
                c = C[i+1][j]
                d[i+1][j].add(n+c)
                d[i+1][j].add(abs(n-c))
            if j+1<W:
                c = C[i][j+1]
                d[i][j+1].add(n+c)
                d[i][j+1].add(abs(n-c))
ans = min(abs(o) for o in d[-1][-1])
print(ans)

Fixed submission:
H,W = map(int,input().split())
A = [list(map(int,input().split())) for _ in [0]*H]
B = [list(map(int,input().split())) for _ in [0]*H]


C = [[abs(b-a) for a,b in zip(a_row,b_row)] for a_row,b_row in zip(A,B)]

dm = [[0]*W for _ in [0]*H]
dm[-1][-1] = 80
for i in range(H-1,-1,-1):
    for j in range(W-1,-1,-1):
        c = C[i][j]
        if i-1>=0:
            dm[i-1][j] = max(dm[i-1][j],dm[i][j] + c)
        if j-1>=0:
            dm[i][j-1] = max(dm[i][j-1],dm[i][j] + c)

d = [[set() for _ in [0]*W] for _ in [0]*H]
d[0][0] = {C[0][0]}

for i in range(H):
    for j in range(W):
        for n in d[i][j]:
            if i+1<H:
                c = C[i+1][j]
                if n+c <= dm[i][j]:
                    d[i+1][j].add(n+c)
                if n-c <= dm[i][j]:
                    d[i+1][j].add(abs(n-c))
            if j+1<W:
                c = C[i][j+1]
                if n+c <= dm[i][j]:
                    d[i][j+1].add(n+c)
                if n-c <= dm[i][j]:
                    d[i][j+1].add(abs(n-c))
ans = min(abs(o) for o in d[-1][-1])
print(ans)