//Think twice,code once.
#include<bits/stdc++.h>
#define endl '\n'
#define INF 0x3f3f3f3f3f3f3f
#define inf 0x3f3f3f3f
#define ff first
#define ss second
#define int long long
#define pii pair<int,int>
#define mem(i,n) memset(i,n,sizeof i)
#define dg(a) std::cout << #a << " = " << a << endl
typedef long long ll;
typedef unsigned long long ull;
using namespace std;

void solve()
{
    int n,m,k;
    cin >> n >> m >> k;
    vector<char>c(n+2);
    vector<int>sum(n+2);
    vector<int>b(n+1);
    for(int i=1;i<=n;i++)
    {
        cin >> c[i];
        if(c[i]=='1')
        {
            sum[i]++;
        }
        sum[i]+=sum[i-1];
    }
    sum[n+1]=sum[n];
    int cnt=0;
    for(int i=1;i<=n;i++)
    {
        b[i]=cnt;
        if(c[i]=='0') cnt=i;
    }
    auto check=[&](int x){
        if(x==0) return true;
        vector<vector<int>>f(n+2,vector<int>(6,inf));
        for(int i=0;i<=n+1;i++)
        {
            f[i][0]=0;
        }
        for(int i=x;i<=n+1;i++)
        {
            
            if(c[i]=='1') continue;
            for(int j=1;j<=k;j++)
            {
                int pre=b[i-x];
                f[i][j]=min(f[i-1][j],f[pre][j-1]+(i-pre-1)-(sum[i]-sum[pre]));
            }
        }
        return f[n+1][k]<=m;
    };
    int l=0,r=n;
    while(l<r)
    {
        int mid=l+r+1>>1;
        if(check(mid)) l=mid;
        else r=mid-1;
    }
    if(l==0)
    {
        cout << -1 << endl;
    }
    else
    {
        cout << l << endl;
    }
}

int32_t main()
{
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);
    std::cout.tie(nullptr);
    int t = 1;
    // std::cin >> t;
    while(t--) solve();
    return 0;
}