Help me in solving ICL16A problem

My issue

I didn’t understood the problem. Can You give the related rosources?

My code

using namespace std;
int n,m;
int main()

    vector<vector<char>>r(n, vector<char>(m));
    for(int i=0; i<n; i++)
        for(int j=0; j<m; j++)

    int mxx=-1;
    for(int i=0; i+1<n; i++)
        for(int j=0; j<m; j++)
            int temp=abs(r[i+1][j]-r[i][j]);
            mxx= max(mxx, temp);

    return 0;

Problem Link: ICL16A Problem - CodeChef