#include <iostream>
#include <map>
#include <string>
#include <map>
#include <set>
#include <vector>

#define MODC 1000000007

using namespace std;

vector<vector<int>> tab;
int compute(string & r, int pos, int ones) {
	if(pos<=r.size() && ones==0) return 1;
	if(pos>=r.size() || ones<=0) return 0;

	int res=0;
	if(r[pos]=='1') {
		res+=tab[r.size()-pos-1][ones];
		res%=MODC;
		//cout<<res<<"A"<<endl;
		res+=compute(r, pos+1, ones-1);
		res%=MODC;
	}else {
		res+=compute(r, pos+1, ones);
		res%=MODC;
	}
	//cout<<pos<<' '<<ones<<' '<<res<<endl;

	return res;
}

/*int compute(string r, int ones) {
	int res=0;
	for(unsigned i=0; i<r.size(); i++) {
		if(ones==0) { res++;   break;}

		if(r[i]=='1') {
			res+=tab[r.size()-i-1][ones];
			res%=MODC;
			ones--;
		}
		// opravdu nic pokud je tam nula? jo
	}

	return res;
}*/

int main(int argc, char * * argv) {
	int n, k;
	cin>>n>>k;
	tab=vector<vector<int>>(n+1, vector<int>(k+1));
	
	for(int i=0; i<=k; i++) {
		tab[0][i]=0;
	}
	tab[0][0]=1;

	for(int i=1; i<=n; i++) {
		for(int j=0; j<=k; j++) {
			tab[i][j]=tab[i-1][j]+tab[i-1][j-1];
			tab[i][j]%=MODC;
			//cout<<tab[i][j]<<" ";
		}
		//cout<<endl;
	}
	

	string r="";
	char c;
	for(int i=1; i<=n; i++) {
		cin>>c;
		r+=c;
	}

	int res;

	string newr=r;
	int presun=0;

	//int last=r.size()-1;

	for(int i=r.size()-1; i>=0; i--) {
		int tmp=presun+1+(newr[i]-'0');
		newr[i]='0'+(tmp%2);
		presun=tmp/2;
	}
	if(presun==1)
		newr="1"+newr;

	//cout<<r<<endl;
	//cout<<newr<<endl;
	

	res=compute(newr, 0, k);
	//cout<<res<<endl;

	res-=compute(r, 0, k);
	res+=MODC;
	res%=MODC;


	// dirty hack
	int sum=0;
	for(int i=0;i<r.size();i++) {
		if(r[i]=='1') sum++;
	}

	if(sum==k) res++;
	res%=MODC;


	cout<<res<<endl;
	


	return 0;
}