import sys
input = sys.stdin.readline

mod=10**9+7

H,W=map(int,input().split())
MAP=[input().strip() for i in range(H)]

#H,W=200,200
#MAP=["a"*W for i in range(H)]

if MAP[0][0]!=MAP[-1][-1]:
    print(0)
    exit()
def cc(x,y,z,w):
    return x*8000000+y*40000+z*200+w

def re(r):
    w=r%200
    r//=200
    z=r%200
    r//=200
    y=r%200
    x=r//200

    return x,y,z,w

DP=dict()
DP[cc(0,0,H-1,W-1)]=1

for i in range((H+W-2)//2):
    NDP=dict()

    for r in DP:
        x,y,z,w=re(r)
        if 0<=x<H and 0<=z<H and 0<=y+1<W and 0<=w-1<W and MAP[x][y+1]==MAP[z][w-1]:
            if cc(x,y+1,z,w-1) in NDP:
                NDP[cc(x,y+1,z,w-1)]+=DP[cc(x,y,z,w)]
                NDP[cc(x,y+1,z,w-1)]%=mod
            else:
                NDP[cc(x,y+1,z,w-1)]=DP[cc(x,y,z,w)]
                

        if 0<=x<H and 0<=z-1<H and 0<=y+1<W and 0<=w<W and MAP[x][y+1]==MAP[z-1][w]:
            if cc(x,y+1,z-1,w) in NDP:
                NDP[cc(x,y+1,z-1,w)]+=DP[cc(x,y,z,w)]
                NDP[cc(x,y+1,z-1,w)]%=mod
            else:
                NDP[cc(x,y+1,z-1,w)]=DP[cc(x,y,z,w)]

        if 0<=x+1<H and 0<=z<H and 0<=y<W and 0<=w-1<W and MAP[x+1][y]==MAP[z][w-1]:
            if cc(x+1,y,z,w-1) in NDP:
                NDP[cc(x+1,y,z,w-1)]+=DP[cc(x,y,z,w)]
                NDP[cc(x+1,y,z,w-1)]%=mod
            else:
                NDP[cc(x+1,y,z,w-1)]=DP[cc(x,y,z,w)]

        if 0<=x+1<H and 0<=z-1<H and 0<=y<W and 0<=w<W and MAP[x+1][y]==MAP[z-1][w]:
            if cc(x+1,y,z-1,w) in NDP:
                NDP[cc(x+1,y,z-1,w)]+=DP[cc(x,y,z,w)]
                NDP[cc(x+1,y,z-1,w)]%=mod
            else:
                NDP[cc(x+1,y,z-1,w)]=DP[cc(x,y,z,w)]

    DP=NDP

if (H+W)%2==0:
    ANS=0
    for r in DP:
        x,y,z,w=re(r)
        if x==z and y==w:
            ANS+=DP[cc(x,y,z,w)]
            ANS%=mod
    print(ANS)
    
else:
    ANS=0
    for r in DP:
        x,y,z,w=re(r)
        if x==z and y+1==w:
            ANS+=DP[cc(x,y,z,w)]
            ANS%=mod
        if x+1==z and y==w:
            ANS+=DP[cc(x,y,z,w)]
            ANS%=mod
            
    print(ANS)