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

char*mmap();
#define RD(v) int v=0;{int _c;while(_c=*rp++-48,_c>=0)v=v*10+_c;}

char wbuf[1<<28];

main(){
	char*rp=mmap(0l,1l<<28,1,2,0,0ll);
	RD(n);
	RD(k);
	if(k<4){
		if(k==1&n>2|k==2&n>4|k==3&n>8){
			strcpy(wbuf,"-1");
			n=2;
		}else{
			strcpy(wbuf,k==1?"01":k==2?"0011":"00010111");
		}
	}else{
		memset(wbuf,'0',k);
		long*wp=(long*)(wbuf+k);
		long v0=*(long*)"10110010";
		long v1=*(long*)"11001011";
		long v2=*(long*)"00101100";
		for(int j=n-k;j>0;j-=24){
			*wp++=v0;
			*wp++=v1;
			*wp++=v2;
		}
	}
	wbuf[n]=10;
	write(1,wbuf,n+1);
}