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

#define ll long long 
#define lll __int128
#define INF 0x3f3f3f3f
#define LNF 0x3f3f3f3f3f3f3f3fll
#define MOD 998244353
#define pii pair<int, int>
#define pll pair<ll, ll>
#define ld long double
#define fi first
#define se second
#define all(a) a.begin(), a.end()

#define N 200010

int dp[N][10][2];
int pre[N];

int main() {
#ifdef TEST
    freopen("zz.in", "r+", stdin);
#endif
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int n, M, k; cin >> n >> M >> k;
    string s; cin >> s; s = "?" + s;
    for (int i = 1; i <= n; ++ i) pre[i] = pre[i-1] + (s[i] == '0');

    int l = 0, r = n;
    while (l < r) {
        int m = (l+r)>>1;
        memset(dp, 0x3f, sizeof dp);
        dp[0][0][0] = dp[0][0][1] = 0;
        for (int i = 1; i <= n; ++ i) {
            for (int j = 0; j <= k; ++ j) {
                dp[i][j][1] = min(dp[i][j][1], dp[i-1][j][1] + (s[i] == '0'));
                if (i >= m) dp[i][j][1] = min(dp[i][j][1], dp[i-m][j-1][0] + pre[i] - pre[i-m]);
                dp[i][j][0] = min(dp[i-1][j][0], dp[i-1][j][1]) + (s[i] == '1');
            }
        }
        if (min(dp[n][k][0], dp[n][k][1]) <= M) {
            l = m+1;
        } else {
            r = m;
        }
    }
    cout << ((l-1) ? (l-1) : -1) << '\n';
}