matrix

def spiralPal(m, n, a):
    k = 0
    l = 0

    outarr=[]

    checkpal=""

    while (k < m and l < n):

        for i in range(l, n):
            checkpal+=a[k][i]

            if len(checkpal)>1 and checkpal==checkpal[::-1]:
                outarr.append(checkpal)
                checkpal=""

        k += 1

        for i in range(k, m):
            checkpal+=a[i][n - 1]

            if len(checkpal)>1 and checkpal==checkpal[::-1]:
                outarr.append(checkpal)
                checkpal=""

        n -= 1

        if (k < m):

            for i in range(n - 1, (l - 1), -1):
                checkpal+=a[m - 1][i]

                if len(checkpal)>1 and checkpal==checkpal[::-1]:
                    outarr.append(checkpal)
                    checkpal=""

            m -= 1

        if (l < n):

            for i in range(m - 1, k - 1, -1):

                checkpal+=a[i][l]

                if len(checkpal)>1 and checkpal==checkpal[::-1]:
                    outarr.append(checkpal)
                    checkpal=""

            l += 1

    if len(checkpal)!=0:
        outarr.append(checkpal)

    print(*outarr,sep=",")


m=int(input())
inmatrix=[]
for i in range(m):
    inmatrix.append(list(input().split(",")))


R = m
C = len(inmatrix[0])

spiralPal(R, C, inmatrix)