#pragma comment(linker, "/STACK:1024000000,1024000000")#include<cstdio>#include<cstring>#include<cmath>#include<algorithm>#include<vector>#include<map>#include<set>#include<queue>#include<stack>#include<iostream>using namespace std;typedef long long LL;const double pi=acos(-1.0),eps=1e-6;void File(){    freopen("D:\\in.txt","r",stdin);    freopen("D:\\out.txt","w",stdout);}template <class T>inline void read(T &x){    char c=getchar(); x=0;    while(!isdigit(c)) c=getchar();    while(isdigit(c)) {x=x*10+c-‘0‘; c=getchar();}}const int maxn=100010;int n,k,p[maxn],sz;char s[maxn];int get(int x,int low,int high){    return max(p[x]-p[low],p[high]-p[x]);}int f(int L,int R){    int t1,t2; int low=L,high=R;    for(int i=1;i<=200;i++)    {        t1=(low+high)/2;        t2=(t1+high)/2;        if (get(t1,L,R)<get(t2,L,R)) high=t2;        else low=t1;    }    return get(t1,L,R);}int main(){    scanf("%d%d",&n,&k);    scanf("%s",s);    for(int i=0;s[i];i++)    {        if(s[i]==‘1‘) continue;        sz++; p[sz]=i+1;    }    int ans=200000;    for(int i=1;i<=sz;i++)    {        if(i+k>sz) break;        ans=min(ans,f(i,i+k));    }    printf("%d\n",ans);    return 0;}