#include <iostream>

#include <sstream>

#include <algorithm>

#include <cstdio>

#include <math.h>

#include <set>

#include <map>

#include <queue>

#include <string>

#include <string.h>

#include <bitset>

#define REP(i,a,n) for(int i=a;i<=n;++i)

#define PER(i,a,n) for(int i=n;i>=a;--i)

#define hr putchar(10)

#define pb push_back

#define lc (o<<1)

#define rc (lc|1)

#define mid ((l+r)>>1)

#define ls lc,l,mid

#define rs rc,mid+1,r

#define x first

#define y second

#define io std::ios::sync_with_stdio(false)

#define endl '\n'

#define DB(a) ({REP(__i,1,n) cout<<a[__i]<<' ';hr;})

using namespace std;

typedef long long ll;

typedef pair<int,int> pii;

const int P = 1e9+7, INF = 0x3f3f3f3f;

ll gcd(ll a,ll b) {return b?gcd(b,a%b):a;}

ll qpow(ll a,ll n) {ll r=1%P;for (a%=P;n;a=a*a%P,n>>=1)if(n&1)r=r*a%P;return r;}

ll inv(ll x){return x<=1?1:inv(P%x)*(P-P/x)%P;}

inline int rd() {int x=0;char p=getchar();while(p<'0'||p>'9')p=getchar();while(p>='0'&&p<='9')x=x*10+p-'0',p=getchar();return x;}

//head

#ifdef ONLINE_JUDGE

const int N = 510;

#else

const int N = 111;

#endif

int n, m, k, tot;

char s[N][N];

int f[N][N], g[N][N], dp[N][N];

int main() {

	scanf("%d%d%d", &n, &m, &k);

	REP(i,1,n) scanf("%s",s[i]+1);

	REP(i,1,n) {

		vector<int> v;

		REP(j,1,m) if (s[i][j]=='1') v.pb(j);

		int sz=v.size();

		if (sz) {

			memset(dp,0,sizeof dp);

			v.insert(v.begin(),0);

			PER(len,1,sz-1) {

				REP(L,1,sz+1-len) {

					int R = L+len-1;

					if (L!=1) dp[L][R]=max(dp[L][R],dp[L-1][R]+v[L]-v[L-1]);

					if (R!=sz) dp[L][R]=max(dp[L][R],dp[L][R+1]+v[R+1]-v[R]);

					f[i][sz-len]=max(f[i][sz-len],dp[L][R]);

				}

			}

			f[i][sz] = f[i][sz-1]+1;

			tot += v[sz]-v[1]+1;

		}

		REP(j,0,k) REP(jj,0,min(j,sz)) {

			g[i][j]=max(g[i][j],g[i-1][j-jj]+f[i][jj]);

		}

	}

	printf("%d\n", tot-g[n][k]);

}