smp=open("sample.txt","r+")
sq=smp.readlines()
for i in range(len(sq)):
    sq[i]=sq[i].split("\n")
    sq[i]="".join(sq[i])
    sq[i]=sq[i].split(" ")
x=len(sq[1])
y=len(sq)
def big(array,x1,y1,x2,y2):
    ans=0
    for i in range(y2+1-y1):
        for x in range(x2+1-x1):
            ans+=int(array[i+y1][x+x1])
    return ans
ans=int(sq[0][0])
for i in range(y):
    for j in range(x):
        for i2 in range(y-i):
            for j2 in range(x-j):
                if(big(sq,j,i,j+j2,i+i2)>ans):
                    ans=big(sq,j,i,j+j2,i+i2)
print(ans)

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