#include<bits/stdc++.h>
#define fr(i,j,k) for(register int i=j;i<=k;++i)
#define rf(i,j,k) for(register int i=j;i>=k;--i)
#define foredge(i,j) for(register int i=head[j];i;i=e[i].nxt)
#define pb push_back
#define Times printf("Time:%.3lf\n",clock()/CLOCKS_PER_SEC)
using namespace std;
inline int read(){
	int x=0;
	bool f=0;
	char c=getchar();
	while(!isdigit(c)) f|=(c=='-'),c=getchar();
	while(isdigit(c)) x=(x<<3)+(x<<1)+(c^48),c=getchar();
	return f?-x:x;
}
inline void write(int x){
    if(x<0){putchar('-');x=-x;}
    if(x>9)write(x/10);
    putchar(x%10+'0');
}
inline void writeln(int x){write(x); puts("");}
inline void writepl(int x){write(x); putchar(' ');}
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
inline int randfind(int l,int r){return rnd()%(r-l+1)+l;}
//inline void init(){
//	int t=read();
//	while(t--) work();
//}
int n,m;
char c[20][20];
inline bool check(int l,int r,int ln1,int ln2){
    // cout<<l<<' '<<r<<' '<<ln1<<' '<<ln2<<endl;
    if(l+ln1-1>n) return false;
    if(r+ln2-1>m) return false;
    fr(i,l,l+ln1-1) fr(j,r,r+ln2-1) if(c[i][j]=='0') return false;
    return true;
}
inline void work(){
    fr(i,1,n) scanf("%s",c[i]+1);
    int num=0;
    fr(i,1,n) fr(j,1,m) num+=(c[i][j]=='1');
    // cout<<num<<endl;
    fr(i,1,n) fr(j,1,m) fr(x,1,n-i+1){
        if(num%x!=0) continue;
        if(check(i,j,x,num/x)){
            puts("Yes");
            return;
        }
    }
    puts("No");
}
inline void init(){
    while(cin>>n>>m) work();
}
signed main(){
	// freopen("input.in","r",stdin);
	// freopen("output.out","w",stdout);
    init();
    // printf("\nTIME:%.3lf",(double)clock()/CLOCKS_PER_SEC);
	return 0;
}