#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

#define rd() ({long _v=0,_c;while(_c=*rp++-48,_c>=0)_v=_v*10+_c;_v;})
#define wt(v) {ulong _z=v;do*--wp=_z%10+48;while(_z/=10);}
#define rep(v,e) for(long v=0;v<e;++v)
#define rep3(v,s,e) for(long v=s;v<e;++v)
#define rrep(v,e) for(long v=e;v--;)

typedef unsigned long ulong;

#define MD 1000000007

unsigned src[402][402],dst[402][402];
char*s;
long h,w;

char at(int y,int x){
	return s[x+y*(w+1)];
}

int main(){
	{
		char*mmap();
		char*rp=mmap(0l,1l<<25,1,2,0,0ll);
		h=rd();
		w=rd();
		s=rp;
	}
	if((h+w&1)==0){
		long st=h<=w?0:h-w>>1;
		long ed=st+(h<=w?h:w);
		rep3(y,st,ed){
			src[y+1][y+1]=1;
		}
	}
	else{
		long st=h<=w?0:h-w>>1;
		long ed=st+(h<=w?h:w);
		rep3(y,st,ed){
			if(at(y,(w+h>>1)-y-1)==at(y,(w+h>>1)-y)){
				src[y+1][y+1]=1;
			}
			if(at(y,(w+h>>1)-y-1)==at(y+1,(w+h>>1)-y-1)){
				src[y+1][y+2]=1;
			}
		}
	}
	rrep(i,(w+h>>1)-1){
		long l=i+1;
		l=l<=h?l:h;
		l=l<=w?l:w;
		long st=i<w?0:i-1-w;
		long ed=st+l;
		rep3(y1,st,ed){
			rep3(y2,h-ed,h-st){
				if(at(y1,i-y1)==at(y2,h+w-2-i-y2)){
					dst[y1+1][y2+1]=(0ul+src[y1+1][y2+1]+src[y1+1][y2+0]+src[y1+2][y2+1]+src[y1+2][y2+0])%MD;
				}
			}
		}
		rep(j,402){
			rep(k,402){
				src[j][k]=dst[j][k];
				dst[j][k]=0;
			}
		}
	}

	char wbuf[64],*wp=wbuf+sizeof wbuf;
	wt(src[1][h]);
	write(1,wp,wbuf+sizeof wbuf-wp);
	_exit(0);
}