C++ :

#include<stdio.h>
#include<string.h>
int n,m,r,c;
int mp[20][20];
int chose[20];
int dp[20][20];
int res=0x3f3f3f3f;
inline int myabs(int a){
    return a>=0?a:-a;
}
inline int mymax(int a,int b){
    return a>b?a:b;
}
inline int mymin(int a,int b){
    return a<b?a:b;
}
void solve(){
    memset(dp,0x3f,sizeof(dp));
    int f[20][20];
    for(int i=1;i<m;i++){
        for(int j=i+1;j<=m;j++){
            f[i][j]=0;
            for(int k=0;k<r;k++){
                f[i][j]+=myabs(mp[chose[k]][i]-mp[chose[k]][j]);
            }
        }
    }
    int col[20];
    for(int i=1;i<=m;i++){
        col[i]=0;
        for(int j=1;j<r;j++){
            col[i]+=myabs(mp[chose[j]][i]-mp[chose[j-1]][i]);
        }
    }
    for(int i=1;i<=m;i++){
        dp[i][1]=col[i];
    }
    for(int i=2;i<=m;i++){
        int minc=i<c?i:c;
        for(int j=2;j<=minc;j++){
            for(int k=j-1;k<i;k++){
                dp[i][j]=mymin(dp[i][j],dp[k][j-1]+col[i]+f[k][i]);
            }
        }
    }
    for(int i=c;i<=m;i++){
        res=mymin(dp[i][c],res);
    }
}
void dfs(int x,int now){
    if(x==r){
        solve();
        return;
    }
    if(r-x>n-now+1)return;
    for(int i=now;i<=n;i++){
        chose[x]=i;
        dfs(x+1,i+1);
    }
} 
int main(){
    scanf("%d%d",&n,&m);
    scanf("%d%d",&r,&c);
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            scanf("%d",mp[i]+j);
        }
    }
    dfs(0,1);
    printf("%d\n",res);
    return 0;
} 

Pascal :

var
        l:array[0..21]of longint;
        a:array[0..21,0..21]of longint;
        n,m,i,j,k,x,y,z,s,ls,r,c:longint;
function min(x,y:longint):longint;
begin
        if x<y then exit(x)
        else exit(y);
end;
procedure dp;
var
        i,j,k:longint;
        f,d:array[0..21,0..21]of longint;
begin
        for i:=0 to n do
        for j:=0 to n do
        f[i,j]:=maxlongint;
        fillchar(d,sizeof(d),0);
        for i:=0 to n do
        for j:=i+1 to n do
        begin
                d[i,j]:=0;
                if i<>0 then
                for k:=1 to c do
                inc(d[i,j],abs(a[j,l[k]]-a[i,l[k]]));
                for k:=1 to c-1 do
                inc(d[i,j],abs(a[j,l[k]]-a[j,l[k+1]]));
        end;
        f[0,0]:=0;
        for i:=1 to n do
        for j:=1 to min(r,i) do
        begin
                for k:=i-1 downto 0 do
                if f[k,j-1]<>maxlongint then
                begin
                        f[i,j]:=min(f[i,j],f[k,j-1]+d[k,i]);
                end;
        end;
        for i:=r to n do
        s:=min(s,f[i,r]);
end;
procedure dg(k:longint);
begin
        if l[0]=c then
        begin
                dp;
                exit;
        end;
        if k>m then exit;
        inc(l[0]);
        l[l[0]]:=k;
        dg(k+1);
        dec(l[0]);
        dg(k+1);
end;
begin
      //  assign(input,'submatrix.in');
     //   reset(input);
     //   assign(output,'submatrix.out');
    //    rewrite(output);
        readln(n,m,r,c);
        for i:=1 to n do
        for j:=1 to m do
        read(a[i,j]);
        s:=maxlongint;
        dg(1);
        writeln(s);
end.