#include <bits/stdc++.h>
#define maxn 1000007
#define int long long
#define dl long double
#define mod 1000000007
using namespace std;
inline int pls(int a, int b) {int m = a + b; return m < mod ? m : m - mod;}
inline int dec(int a, int b) {int m = a - b; return m < 0 ? m + mod : m;}
inline int mul(int a, int b) {return 1ll * a * b % mod;}
inline int fpow(int a, int b) {
  int ans = 1;
  for(; b; b >>= 1,a = mul(a, a)) if(b & 1) ans = mul(ans, a);
  return ans;
}
inline int inv(int a) {return fpow(a, mod - 2);}
inline int dvi(int a, int b) {return mul(a, inv(b));};
inline int qread() {
  char c = getchar(); int num = 0, f = 1;
  for(; !isdigit(c); c=getchar()) if(c == '-') f = -1;
  for(; isdigit(c); c=getchar()) num = num * 10 + c - '0';
  return num * f;
}
const int inf = 0x3f3f3f3f3f3f3f3f;
int n, m, k;
char s[maxn];
int num[maxn], dp[maxn][6][2];
int get(int l, int r) {
  return num[r] - num[l - 1];
}
int check(int u) {
  
  dp[0][0][1] = inf;
  for(int j = 1; j <= k; ++j) dp[0][j][0] = dp[0][j][1] = inf;
  for(int i = 1; i <= n; ++i) {
    for(int j = 1; j <= k; ++j) {
      dp[i][j][0] = dp[i][j][1] = inf;
      if(i < u) continue;
      if(s[i] == '0') {
        dp[i][j][0] = min(dp[i - 1][j][1], dp[i - 1][j][0]);
      } 
      dp[i][j][1] = min(dp[i - u][j - 1][0], dp[i - u][j][1]) + get(i - u + 1, i);
    }
  }
  
  return min(dp[n][k][0], dp[n][k][1]) <= m;
}
signed main() {
  n = qread(), m = qread(), k = qread();
  scanf("%s", s + 1);
  for(int i = 1; i <= n; ++i) {
    num[i] = (s[i] == '0') + num[i - 1];
  }
  
  int l = 1, r = n;
  int mid, res = -1;
  while(l <= r) {
    mid = (l + r) >> 1;
    if(check(mid)) {
      res = mid;
      l = mid + 1;
    } else {
      r = mid - 1;
    }
  }
  cout << res << '\n';
  return 0;
}