#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ld=double;
using pll=pair<ll,ll>;
using vll=vector<ll>;
using vpll=vector<pll>;
using vvll=vector<vll>;
#define FOR(i,a,b) for(ll i=a;i<(ll)b;++i)
#define ROF(i,a,b) for(ll i=a;i>=(ll)b;--i)
#define F(n) FOR(i,0,n)
#define FF(n) FOR(j,0,n)
#define aa first
#define bb second
#define PB push_back

#define MX 1007
ll DP[MX][MX][2];
#define MOD 1000000007

ll n,k;
string s;
ll dp(ll pos, ll k, ll c){
  ll &ret = DP[pos][k][c];
  if(pos==n) {
    return ret=k==c;
  }
  ret = 0;
  if(k-(c+s[pos])%2 >=0) ret = (ret+(dp(pos+1, k-(c+s[pos])%2, (c+s[pos])/2)))%MOD;
  if(k-(c+s[pos]+1)%2 >=0) ret = (ret+(dp(pos+1, k-(1+c+s[pos])%2, (1+c+s[pos])/2)))%MOD;
  return ret;
}

int main(){
  ios::sync_with_stdio(0);
  memset(DP,-1,sizeof DP);
  cin >> n >> k;
  cin>>s;
  reverse(s.begin(),s.end());
  for(auto &c:s) c-='0';
  cout << dp(0,k,0) << endl;
  return 0;
}