Buggy python submission (verdict: Runtime Error):
import time
t1 = time.time()
h,w = map(int,input().split())
grid = []
for i in range(h):
    grid.append(list(map(int,input().split())))
for i in range(h):
    lsti = list(map(int,input().split()))
    for j in range(w):
        grid[i][j] = abs(grid[i][j]-lst[j])
lst = [[set() for _ in range(w)] for _ in range(h)]
lst[0][0].add(grid[0][0])
for j in range(1,w):
    for x in lst[0][j-1]:
        lst[0][j].add(abs(grid[0][j]-x))
        if (grid[0][j] + x) <= 6400:
            lst[0][j].add(grid[0][j]+x)
for i in range(1,h):
    for x in lst[i-1][0]:
        lst[i][0].add(abs(grid[i][0]-x))
        if grid[i][0] + x <= 6400:
            lst[i][0].add(grid[i][0]+x)
for i in range(1,h):
    for j in range(1,w):
        for x in lst[i][j-1]:
            lst[i][j].add(abs(grid[i][j]-x))
            if grid[i][j] + x <= 6400:
                lst[i][j].add(grid[i][j]+x)
        for x in lst[i-1][j]:
            lst[i][j].add(abs(grid[i][j]-x))
            if grid[i][j] + x <= 6400:
                lst[i][j].add(grid[i][j]+x)
        t = time.time()
        if t - t1 > 1.8:
            print(0)
            exit()
print(min(lst[h-1][w-1]))

Fixed submission:
import time
t1 = time.time()
h,w = map(int,input().split())
grid = []
for i in range(h):
    grid.append(list(map(int,input().split())))
for i in range(h):
    lst = list(map(int,input().split()))
    for j in range(w):
        grid[i][j] = abs(grid[i][j]-lst[j])
lst = [[set() for _ in range(w)] for _ in range(h)]
lst[0][0].add(grid[0][0])
for j in range(1,w):
    for x in lst[0][j-1]:
        lst[0][j].add(abs(grid[0][j]-x))
        if (grid[0][j] + x) <= 6400:
            lst[0][j].add(grid[0][j]+x)
for i in range(1,h):
    for x in lst[i-1][0]:
        lst[i][0].add(abs(grid[i][0]-x))
        if grid[i][0] + x <= 6400:
            lst[i][0].add(grid[i][0]+x)
for i in range(1,h):
    for j in range(1,w):
        for x in lst[i][j-1]:
            lst[i][j].add(abs(grid[i][j]-x))
            if grid[i][j] + x <= 6400:
                lst[i][j].add(grid[i][j]+x)
        for x in lst[i-1][j]:
            lst[i][j].add(abs(grid[i][j]-x))
            if grid[i][j] + x <= 6400:
                lst[i][j].add(grid[i][j]+x)
        t = time.time()
        if t - t1 > 1.8:
            print(0)
            exit()
print(min(lst[h-1][w-1]))

Buggy python submission (verdict: Time Limit Exceeded):
h,w = map(int,input().split())
grid = []
for i in range(h):
    grid.append(list(map(int,input().split())))
for i in range(h):
    lst = list(map(int,input().split()))
    for j in range(w):
        grid[i][j] = abs(grid[i][j]-lst[j])
lst = [[set() for _ in range(w)] for _ in range(h)]
lst[0][0].add(grid[0][0])
for j in range(1,w):
    for x in lst[0][j-1]:
        lst[0][j].add(abs(grid[0][j]-x))
        if grid[0][j] + x <= 6400:
            lst[0][j].add(grid[0][j]+x)
for i in range(1,h):
    for x in lst[i-1][0]:
        lst[i][0].add(abs(grid[i][0]-x))
        if grid[i][0] + x <= 6400:
            lst[i][0].add(grid[i][0]+x)
for i in range(1,h):
    for j in range(1,w):
        for x in lst[i][j-1]:
            lst[i][j].add(abs(grid[i][j]-x))
            if grid[i][j] + x <= 6400:
                lst[i][j].add(grid[i][j]+x)
        for x in lst[i-1][j]:
            lst[i][j].add(abs(grid[i][j]-x))
            if grid[i][j] + x <= 6400:
                lst[i][j].add(grid[i][j]+x)
print(min(lst[h-1][w-1]))

Fixed submission:
import time
t1 = time.time()
h,w = map(int,input().split())
grid = []
for i in range(h):
    grid.append(list(map(int,input().split())))
for i in range(h):
    lst = list(map(int,input().split()))
    for j in range(w):
        grid[i][j] = abs(grid[i][j]-lst[j])
lst = [[set() for _ in range(w)] for _ in range(h)]
lst[0][0].add(grid[0][0])
for j in range(1,w):
    for x in lst[0][j-1]:
        lst[0][j].add(abs(grid[0][j]-x))
        if (grid[0][j] + x) <= 6400:
            lst[0][j].add(grid[0][j]+x)
for i in range(1,h):
    for x in lst[i-1][0]:
        lst[i][0].add(abs(grid[i][0]-x))
        if grid[i][0] + x <= 6400:
            lst[i][0].add(grid[i][0]+x)
for i in range(1,h):
    for j in range(1,w):
        for x in lst[i][j-1]:
            lst[i][j].add(abs(grid[i][j]-x))
            if grid[i][j] + x <= 6400:
                lst[i][j].add(grid[i][j]+x)
        for x in lst[i-1][j]:
            lst[i][j].add(abs(grid[i][j]-x))
            if grid[i][j] + x <= 6400:
                lst[i][j].add(grid[i][j]+x)
        t = time.time()
        if t - t1 > 1.8:
            print(0)
            exit()
print(min(lst[h-1][w-1]))