#include<bits/stdc++.h>
using namespace std;
#define int long long

int f[200010][6][2];
int n,m,k;
int s[200010],sum[200010];
int getsum(int l,int r){return r-l+1-(sum[r]-sum[l-1]);}
bool check(int l){
  memset(f,0x3f,sizeof(f));
  f[0][0][0]=f[0][0][1]=0;
  for(int i=1;i<=n;++i){
    for(int j=0;j<=k;++j){
      if(j&&i>=l)f[i][j][1]=f[i-l][j-1][0]+getsum(i-l+1,i);
      f[i][j][0]=min(f[i-1][j][0],f[i-1][j][1]);
      //cout<<i<<' '<<j<<' '<<f[i][j][0]<<' '<<f[i][j][1]<<endl;
    }
  }
  return min(f[n][k][0],f[n][k][1])<=m;
}
signed main(){
  cin>>n>>m>>k;
  for(int i=1;i<=n;++i)scanf("%1d",&s[i]),sum[i]=sum[i-1]+s[i];
  if(!check(1)){cout<<-1;return 0;}
  int l=1,r=n;
  while(l<r){
    int mid=r-(r-l>>1);
    if(check(mid))l=mid;
    else r=mid-1;
  }
  cout<<l;
  return 0;
}