#include<stdio.h>

int main(){
    int h,w,i,j,hf[131072]={0},wf[131072]={0};
    char s[131072];
    scanf("%d%d",&h,&w);
    for(i=0;i<h;i++){
        scanf("%s",&s[i*w]);
        for(j=0;j<w;j++){
            hf[i]|=(s[i*w+j]-'0'+1);
            wf[j]|=(s[i*w+j]-'0'+1);
        }
    }
    if(h==1){
        if(hf[0]!=3){printf("NO\n");return 0;}else{printf("YES\n");return 0;}
    }
    else if(w==1){
        if(wf[0]!=3){printf("NO\n");return 0;}else{printf("YES\n");return 0;}
    }
    else{
        for(i=0;i<h;i++){
            if(hf[i]!=3){break;}
            if(i==h-1){printf("YES\n");return 0;}
        }
        for(i=0;i<w;i++){
            if(wf[i]!=3){break;}
            if(i==w-1){printf("YES\n");return 0;}
        }
        printf("NO\n");return 0;
    }
    return 0;
}