// what is matter? never mind. 
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,avx2") 
#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define ll long long
//#define int long long
#define ull unsigned long long
using namespace std;
inline int read()
{
	char c=getchar();int x=0;bool f=0;
	for(;!isdigit(c);c=getchar())f^=!(c^45);
	for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
	if(f)x=-x;return x;
}
 
#define mod 998244353
struct modint{
	int x;
	modint(int o=0){x=o;}
	modint &operator = (int o){return x=o,*this;}
	modint &operator +=(modint o){return x=x+o.x>=mod?x+o.x-mod:x+o.x,*this;}
	modint &operator -=(modint o){return x=x-o.x<0?x-o.x+mod:x-o.x,*this;}
	modint &operator *=(modint o){return x=1ll*x*o.x%mod,*this;}
	modint &operator ^=(int b){
		modint a=*this,c=1;
		for(;b;b>>=1,a*=a)if(b&1)c*=a;
		return x=c.x,*this;
	}
	modint &operator /=(modint o){return *this *=o^=mod-2;}
	friend modint operator +(modint a,modint b){return a+=b;}
	friend modint operator -(modint a,modint b){return a-=b;}
	friend modint operator *(modint a,modint b){return a*=b;}
	friend modint operator /(modint a,modint b){return a/=b;}
	friend modint operator ^(modint a,int b){return a^=b;}
	friend bool operator ==(modint a,int b){return a.x==b;}
	friend bool operator !=(modint a,int b){return a.x!=b;}
	bool operator ! () {return !x;}
	modint operator - () {return x?mod-x:0;}
	bool operator <(const modint&b)const{return x<b.x;}
};
inline modint qpow(modint x,int y){return x^y;}

vector<modint> fac,ifac,iv;
inline void initC(int n)
{
	if(iv.empty())fac=ifac=iv=vector<modint>(2,1);
	int m=iv.size(); ++n;
	if(m>=n)return;
	iv.resize(n),fac.resize(n),ifac.resize(n);
	For(i,m,n-1){
		iv[i]=iv[mod%i]*(mod-mod/i);
		fac[i]=fac[i-1]*i,ifac[i]=ifac[i-1]*iv[i];
	}
}
inline modint C(int n,int m){
	if(m<0||n<m)return 0;
	return initC(n),fac[n]*ifac[m]*ifac[n-m];
}
inline modint sign(int n){return (n&1)?(mod-1):(1);}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;

#define maxn 1000005
#define inf 0x3f3f3f3f

int n,m,k;
int sum[maxn];
char s[maxn];

int f[maxn][6][3];

int S(int l,int r,int x){
	int res=sum[r]-sum[l-1];
	if(x) res=r-l+1-res;
	return res;
}

void chkmin(int&x,int y){
	x=min(x,y);
}
bool chk(int mid)
{
	memset(f,63,sizeof f);
	f[1][0][0]=0;
	For(i,1,n+1){
		For(j,0,k){
			chkmin(f[i+1][j][0],f[i][j][0]+(s[i+1]=='1'?1e9:0));
			chkmin(f[i+1][j][0],f[i][j][1]+(s[i+1]=='1'?1e9:0));
			chkmin(f[i+1][j][1],f[i][j][0]+(s[i+1]=='0'));
			chkmin(f[i+1][j][1],f[i][j][1]+(s[i+1]=='0'));
			if(j<k)chkmin(f[i+mid][j+1][1],f[i][j][0]+S(i+1,i+mid,1));
		}
		// if(mid==7)
		// {
			// for(int j=0;j<=k;j++)printf("%d %d,",f[i][j][0],f[i][j][1]);
			// puts("");
		// }
	}
	return min(f[n+1][k][0],f[n+1][k][1])<=m;
}

signed main()
{
	n=read(),m=read(),k=read();
	scanf("%s",s+2);s[1]='0',s[n+2]='0';
	For(i,1,n+2)sum[i]=sum[i-1]+(s[i]&1);
	int res=-1,l=1,r=n;
	while(l<=r){
		int mid=l+r>>1;
		if(chk(mid))res=mid,l=mid+1;
		else r=mid-1;
	}
	cout<<res;
	return 0;
}
/*

*/