#include <iostream>

using namespace std;

int i,j,n,m,a,s[105][105],k,i1,j1,i2,j2,sum,summax;

int main()
{
    cin>>n>>m>>k;
    for(i=1; i<=n; i++)
        for(j=1; j<=m; j++)
            cin>>a, s[i][j]=s[i-1][j]+s[i][j-1]-s[i-1][j-1]+a;
    for(i=1; i<=k; i++)
    {
        cin>>i1>>j1>>i2>>j2;
        sum=0;
        sum=s[i2][j2]-s[i1-1][j2]-s[i2][j1-1]+s[i1-1][j1-1];
        if(sum>summax)
            summax=sum;
    }
    cout<<summax<<'\n';
    return 0;
}