#include <bits/stdc++.h>
using namespace std;
constexpr int maxn = 2e5+10;
int n,m,k,sz[maxn];
// set<int,greater<int>> st;
string s;
int a[maxn];
int count_z(int l, int r) {
    return sz[r] - sz[l-1];
}
bool check(int x) {
    int dp[n+5][6][2];
    memset(dp, 0x3f, sizeof(dp));
    for(int i=1;i<=n;i++) {
        dp[i][0][s[i]-'0'] = 0;
        for(int j=0;j<=k;j++) {
            if(s[i] == '0') {
                dp[i][j][0] = min(dp[i-1][j][0], dp[i-1][j][1]);
            }else{
                dp[i][j][1] = dp[i-1][j][1];
            }
            if(j == 1 && i >= x)
                dp[i][j][1] = min(dp[i][j][1], count_z(1, i));
            if(i-x < 0 || j == 0) continue;
            dp[i][j][1] = min(dp[i][j][1], dp[i-x][j-1][0] + count_z(i-x+1, i));
        }
    }
    return min(dp[n][k][0], dp[n][k][1]) <= m;
}
int main() {
    ios::sync_with_stdio(false);
    cin >> n >> m >> k >> s;
    s = ' ' + s;
    for(int i=1;i<=n;i++) {
        sz[i] = sz[i-1] + (s[i] == '0');
        // if(s[i] == '0')
        //     st.insert(i);
    }
    int l=0,r=n,mid,ans;
    while(l <= r) {
        mid = (l + r) >> 1;
        if(check(mid)) {
            ans = mid;
            l = mid + 1;
        }else{
            r = mid - 1;
        }
    }
    if(ans)
        cout << ans << endl;
    else
        cout << -1 << endl;
}