#include<bits/stdc++.h>

using namespace std;

const int N=;

int n,m,K,a[N][N],ans=1e9;

int sx[N][N],sy[N][N];

inline int read()

{

    char ch=getchar();int num=;bool flag=false;

    while(ch<''||ch>''){if(ch=='-')flag=true;ch=getchar();}

    while(ch>=''&&ch<=''){num=num*+ch-'';ch=getchar();}

    return flag?-num:num;

}

inline int workup(int up)

{

    int x1=,x2=n,y1=,y2=m,ret=,ka;

    while(x1<=x2&&y1<=y2){

        ret++;

        ka=sy[x2][y1]-sy[x1-][y1];

        if(ka<=K){++y1;continue;};

        ka=sy[x2][y2]-sy[x1-][y2];

        if(ka<=K){--y2;continue;}

        ka=sx[x1][y2]-sx[x1][y1-];

        if(ka<=K&&x1<up){++x1;continue;}

        ka=sx[x2][y2]-sx[x2][y1-];

        if(ka<=K){--x2;continue;}

        ret=1e9;break;

    }

    return ret;

}

inline int workle(int left)

{

    int x1=,x2=n,y1=,y2=m,ret=,ka;

    while(x1<=x2&&y1<=y2){

        ret++;

        ka=sx[x1][y2]-sx[x1][y1-];

        if(ka<=K){++x1;continue;}

        ka=sx[x2][y2]-sx[x2][y1-];

        if(ka<=K){--x2;continue;}

        ka=sy[x2][y1]-sy[x1-][y1];

        if(ka<=K&&y1<left){++y1;continue;}

        ka=sy[x2][y2]-sy[x1-][y2];

        if(ka<=K){--y2;continue;}

        ret=1e9;break;

    }

    return ret;

}

int main()

{

    //freopen("ork.in","r",stdin);

    //freopen("ork.out","w",stdout);

    K=read();m=read();n=read();

    for(int i=;i<=n;i++)

    for(int j=;j<=m;j++)

    a[i][j]=read();

    for(int i=;i<=n;i++)

    for(int j=;j<=m;j++){

    sx[i][j]=sx[i][j-]+a[i][j];

    sy[i][j]=sy[i-][j]+a[i][j];}

    for(int i=;i<=n;i++)

    ans=min(ans,workup(i));

    for(int j=;j<=m;j++)

    ans=min(ans,workle(j));

    printf("%d\n",ans);

    return ;

}