#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;

#define rep(i, n) for(int i = 0;i < n;i++)
#define rep1(i, n) for(int i = 1;i < n;i++)
#define repr(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)

#define ALL(a)  (a).begin(),(a).end()

vector<vector<ll>> near8={{-1,1},{0,1},{1,1},{-1,0},{1,0},{-1,-1},{0,-1},{1,-1}};
vector<vector<ll>> near4={{0,1},{-1,0},{1,0},{0,-1}};

ll INF = INT64_MAX;

bool ll_sqrt(ll x, ll& lower_bound, ll& upper_bound)
{
	constexpr ll ll_max = numeric_limits<ll>::max();
 
	bool first_boost = true;
 
	lower_bound = 0;
	upper_bound = x;
	while (upper_bound - lower_bound > 1)
	{
		if (first_boost)
		{
			ll guess = (ll)sqrt((double)x);
			lower_bound = max(guess - 1, (ll)0);
			upper_bound = lower_bound + 3;
			first_boost = false;
		}
 
		ll newval = (lower_bound + upper_bound) / 2;
		if ((newval != 0) && (newval > ll_max / newval))  // newval*newval becomes overflow
			upper_bound = newval;  // because overflow means newval is too big
		else
		{
			ll newval_sqr = newval * newval;
			if (newval_sqr < x)
				lower_bound = newval;
			else
				upper_bound = newval;
		}
	}
 
	if ((upper_bound != 0) && (upper_bound > ll_max / upper_bound))
	{
		if (lower_bound * lower_bound == x)
			upper_bound = lower_bound;
	}
	else
	{
		if (lower_bound * lower_bound == x)
			upper_bound = lower_bound;
		else if (upper_bound * upper_bound == x)
			lower_bound = upper_bound;
	}
	bool is_exact = (lower_bound == upper_bound);
	return is_exact;
}

ll ll_ceil(ll x, int digit);
ll ll_floor(ll x, int digit);


ll ll_floor(ll x, int digit)
{
	if (x < 0)
		return -ll_ceil(-x, digit);
 
	ll div = 1;
	while (digit != 0)
	{
		div *= 10;
		digit--;
	}
	ll modval = x % div;
	ll ans = x - modval;
	return ans;
}

ll ll_ceil(ll x, int digit)
{
	if (x < 0)
		return -ll_floor(-x, digit);
 
	ll div = 1;
	while (digit != 0)
	{
		div *= 10;
		digit--;
	}
	ll modval = x % div;
	ll ans = x - modval;
	if (modval != 0)
		ans += div;
	return ans;
}

struct UnionFind {
    vector<ll> par; // par[i]:iの親の番号　(例) par[3] = 2 : 3の親が2

    UnionFind(ll N) : par(N) { //最初は全てが根であるとして初期化
        for(ll i = 0; i < N; i++) par[i] = i;
    }

    ll root(ll x) { // データxが属する木の根を再帰で得る：root(x) = {xの木の根}
        if (par[x] == x) return x;
        return par[x] = root(par[x]);
    }

    void unite(ll x, ll y) { // xとyの木を併合
        ll rx = root(x); //xの根をrx
        ll ry = root(y); //yの根をry
        if (rx == ry) return; //xとyの根が同じ(=同じ木にある)時はそのまま
        par[rx] = ry; //xとyの根が同じでない(=同じ木にない)時：xの根rxをyの根ryにつける
    }

    bool same(ll x, ll y) { // 2つのデータx, yが属する木が同じならtrueを返す
        ll rx = root(x);
        ll ry = root(y);
        return rx == ry;
    }
};

ll H,W;
vector<vector<char>> map1(501, vector<char>(501,'#'));


bool solve(ll h, ll w){
	ll nexth=0;
	ll nextw=0;

	for(vector<ll> to:near4){
		nexth = h+to[0];
		nextw = w+to[1];
		if(nexth < 0 || nexth >=H || nextw < 0 || nextw >=W || map1[nexth][nextw] == '#'){
			continue;
		}
		if(map1[nexth][nextw] =='g'){
			return true;
		}
		map1[nexth][nextw]='#';
		if(solve(nexth, nextw)){
			return true;
		};
	}

	return false;
}


int main() {
	ll blue,b,c,d, red;
	cin >> blue >> b >> c >> d;
	red = 0;

	ll ans = 0;

	while(true){
		
	if(red * d >= blue){
			break;
	}else if(ans > 100000000){
		ans = -1;
		break;
	}
		blue += b;
		red += c;
		
		ans++;
	}

	cout << ans << endl;

  return 0;
}
#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
using ll=int;
using ld=long double;
using pll=pair<ll, ll>;
//using mint = modint1000000007;
#define rep(i,n) for (ll i=0; i<n; ++i)
#define all(c) begin(c),end(c)
#define PI acos(-1)
#define oo 2e18
template<typename T1, typename T2>
bool chmax(T1 &a,T2 b){if(a<b){a=b;return true;}else return false;}
template<typename T1, typename T2>
bool chmin(T1 &a,T2 b){if(a>b){a=b;return true;}else return false;}
//priority_queue<ll, vector<ll>, greater<ll>> Q;
/*
01234でタイルの方向管理？
*/
#define TIMEOVER_M 12000
#define TIMEOVER 1980000
#define DIV 500

ll T[50][50];
bool B[50][50];
ll P[50][50];
ll D[50][50];
char *ans;
char *W;
ll score=0;
ll high=0;
ll dx[]={0, 1, 0, -1};
ll dy[]={-1, 0, 1, 0};
char dc[]={'U', 'R', 'D', 'L'};
bool all_fin;
bool fin;
clock_t start;
clock_t start_m;
ll loop;
ll node=0;

void steped(ll y, ll x, bool b){
  ll d=D[y][x];
  if (d){
    --d;
    ll ny=y+dy[d];
    ll nx=x+dx[d];
    B[ny][nx]=b;
  }
  B[y][x] = b;
}

// 行き止まりになったら、その時点でのstringを出力
void dfs(ll y, ll x, ll c){// {y, x, 歩数}
  bool used[4]={};
  rep(i, 4){
    clock_t now = clock();
    
    if(now-start_m>TIMEOVER_M) fin=true;
    if(now-start>TIMEOVER) all_fin=true;
    ll r=(node++/DIV)%4;
    while(used[r]) (r+=1)%=4;
    used[r]=true;
    ll ny=y+dy[r];
    ll nx=x+dx[r];
//    cout << "time:" << now-start << endl;
    if(ny<0 || nx<0 || ny>49 || nx>49 || B[ny][nx] || fin || all_fin){
      if(chmax(high, score)){
        if(ans) free(ans);
        ans=strdup(W);
      }
    }
    else{
      //反映
      score+=P[ny][nx];
      W[c]=dc[r];
      steped(ny, nx, true);

      dfs(ny, nx, c+1);
      //復元
      score-=P[ny][nx];
      W[c]='\0';
      steped(ny, nx, false);
    }
  }
    
}

int main(){
  cin.tie(0);
  ios::sync_with_stdio(0);
  cout << fixed << setprecision(10);
  W=(char*)calloc(2000, 1);
  start = clock();
  ll si, sj;
  cin >> si >> sj;
  rep(i, 50) rep(j, 50) cin >> T[i][j];
  rep(i, 50) rep(j, 50) cin >> P[i][j];
  // タイルの方向D
  rep(i, 50) rep(j, 50){
    rep(k, 4){
      ll ny=i+dy[k];
      ll nx=j+dx[k];
      if(ny<0 || nx<0 || ny>49 || nx>49) continue;
      if(T[i][j]==T[ny][nx]) D[i][j]=k+1;
    }
  }
  while(!all_fin){
    loop++;
    fin=false;
    start_m = clock();
    score = P[si][sj];
    chmax(high, score);
    rep(y, 50) rep(x, 50) B[y][x]=false;
    rep(i, 2000) W[i]='\0';
    steped(si, sj, true);
    dfs(si, sj, 0);
  }
//  cout << high << " " << loop << " " << node << endl;
  printf("%s\n", ans);
}
