#include <iostream>

#include <cstring>

#include <vector>

#include <stdlib.h>

using namespace std;

#define endl '\n'

int map[51][51];

int check[51][51] = {0,};

vector<pair<int, int> > v;

int N,L,R;

int people,num;

int dy[4] = {0,0,-1,1};

int dx[4] = {-1,1,0,0};

void dfs(int y, int x){

for(int k=0; k<4; k++){

int ny = y + dy[k];

int nx = x + dx[k];

if((ny<0) || (nx<0) || (ny>=N) || (nx>=N))

continue;

if(check[ny][nx] == 1)

continue;

int diff = abs(map[y][x] - map[ny][nx]);

if(diff>=L && diff<=R){

check[ny][nx] = 1;

num++;

people+=map[ny][nx];

v.push_back(make_pair(ny,nx));

dfs(ny, nx);

}

}

}

int main(int argc, char const *argv[])

{

ios::sync_with_stdio(false);

cin.tie(0);

cin>>N>>L>>R;

for(int i=0; i<N; i++){

for(int j=0; j<N; j++){

cin>>map[i][j];

}

}

int count = 0;

while(1){

memset(check, 0, sizeof(check));

int flag = 0;

for(int i=0; i<N; i++){

for(int j=0; j<N; j++){

if(check[i][j])

continue;

check[i][j] = 1;

people = map[i][j];

num = 1;

v.clear();

v.push_back(make_pair(i,j));

dfs(i,j);

if(num >= 2){

flag = 1;

for(int i=0; i<v.size(); i++)

map[v[i].first][v[i].second] = people/num;

}

}

}

if(flag)

count++;

else

break;

}

cout<<count<<endl;

return 0;

}