#include <bits/stdc++.h>
using namespace std;
// #define int long long
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> PII;
mt19937 rng;
uniform_int_distribution <ull> dist(0,1ull<<63);
//#define mp make_pair
inline void print(__int128 x){//输出模板 
    if(x<0){
        putchar('-');
        x=-x;
    }
    if(x>9) print(x/10);
    putchar(x%10+'0');
}
inline int read()
{
    int X = 0;
    bool flag = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9')
    {
        if (ch == '-')
            flag = 0;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9')
    {
        X = (X << 1) + (X << 3) + ch - '0';
        ch = getchar();
    }
    if (flag)
        return X;
    return ~(X - 1);
}
const ll mod = 1e9 + 7,INF = 0x3f3f3f3f;
ll qpow(ll a, ll b)
{
    ll res = 1;
    a %= mod;
    assert(b >= 0);
    for (; b; b >>= 1)
    {
        if (b & 1)
            res = res * a % mod;
        a = a * a % mod;
    }
    return res;
}
inline int gcd(int a, int b) { return b == 0 ? a : gcd(b, a % b); }
inline int lcm(int a, int b) { return a / gcd(a, b) * b; }
const int N = 200010,M = 1000010;

string s;
int f[N][10][2],sum[N];
int n,m,k;

bool check(int x)
{
    for(int i=0;i<=n;i++)for(int j=1;j<=k;j++) f[i][j][1] = f[i][j][0] = INF;
    f[0][0][0] = 0;
    for(int i=1;i<=n;i++) 
    {
        if(s[i]=='1') f[i][0][1] = 0;
        else f[i][0][0] = 0,f[i][0][1] = 1;
    }
    int tmp[10];
    for(int i=0;i<=k;i++) tmp[i] = INF;
    int res = INF;
    for(int i=x;i<=n;i++)
    {
        for(int j=1;j<=k;j++)
        {
            tmp[j-1] = min(tmp[j-1],f[i-x][j-1][0]-sum[i-x]);
            if(s[i]=='1') f[i][j][1] = min(f[i][j][1],sum[i]+tmp[j-1]);
            else 
            {
                f[i][j][1] = min(f[i][j][1],sum[i]+tmp[j-1]);
                f[i][j][0] = min(f[i-1][j][0],f[i-1][j][1]);
            }
        }
        res = min({res,f[i][k][0],f[i][k][1]});
    }
        
    return res<=m;
}

void solve()
{
    cin>>n>>m>>k;
    cin>>s;
    s = ' '+s;
    for(int i=1;i<=n;i++) sum[i] = sum[i-1]+(s[i]=='0');
    int l = 0,r = n;
    while(r>l)
    {
        int mid = l+r+1>>1;
        if(check(mid)) l = mid;
        else r = mid-1; 
    }
    if(!l) cout<<-1<<'\n';
    else cout<<l<<'\n';
}

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