#pragma GCC optimize ("O3")
#include <iostream>
#include <iomanip>
#include <istream>
#include <ostream>
#include <sstream>
#include <iterator>
#include <vector>
#include <algorithm>
#include <queue>
#include <deque>
#include <list>
#include <stack>
#include <map>
#include <unordered_map>
#include <set>
#include <bitset>
#include <utility>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <ctime>
#include <cctype>
#include <cstdlib>
#include <numeric>
#define IINF 2147483647
#define INF 3223372036854775807
#define MOD 1000000007
#define mod 1000000007
//#define mod 998244353
#define INT_MAX_ 2147483647
#define EPS (1e-10)
#define REP(i, a, n) fo-r (ll i = a; i < (ll)(n); i++)
#define REPE(i, a, n) for (ll i = a; i <= (ll)(n); i++)
//#define rep(i,n)for (ll i = 0; i < (ll)(n); i++)
#define rep(i,l,r)for(ll i=(l);i<(r);i++)
#define rep1(i,n) for(int i=1;i<=(int)(n);i++)
#define Endl endl
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define eb emplace_back
#define mmax(x,y)(x>y?x:y)
#define mmin(x,y)(x<y?x:y)
#define chmax(x,y) x=mmax(x,y)
#define chmin(x,y) x=mmin(x,y)
#define all(x) (x).begin(),(x).end()
#define siz(x) (ll)(x).size()
#define PI acos(-1.0)
#define pi acos(-1.0)
#define me memset
// /#define bit(n,k) ((n>>k)&1)
#define lg length()
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;
typedef long double ld;
typedef pair<int,int>Pin;
typedef pair<ll,ll>Pll;
template<class T> using V=vector<T>;
template<typename T> using min_priority_queue = priority_queue<T, vector<T>, greater<T> >;
long long GCD(long long a, long long b) {return b?GCD(b,a%b):a;}
long long LCM(long long a, long long b) {return a/GCD(a,b)*b;}
ll pom(ll a,ll n,int m){ll x=1;for(a%=m;n;n/=2)n&1?x=x*a%m:0,a=a*a%m;return x;}
#define invp(a,p)pom(a,p-2,p)
int dx[4]={-1,0,1,0};
int dy[4]={0,-1,0,1};
int ddx[8]={-1,0,1,0,1,1,-1,-1};
int ddy[8]={0,-1,0,1,1,-1,1,-1};
ll cmp1(pair<Pll,ll> a,pair<Pll,ll> b){
        return a.fi.se<b.fi.se;
}
ll cmp2(pair<ll,ll> a,pair<ll,ll> b){
    if(a.fi!=b.fi)
        return  a.fi<b.fi;
    else
        return a.se<b.se;
}
//----------------------------------------------------------------------

//----------------------------------------------------------------------
int main(int argc, char * argv[]){
    cin.tie(0);
    ios::sync_with_stdio(false);
    //-------------------------------  
    //ll begin_t=clock();
    //freopen("big.txt", "r", stdin);
    //freopen("out3.txt", "w", stdout);
    //------------------------------
    ll h,w,x,y;cin>>h>>w>>x>>y;
    x--;y--;
    char s[110][110];
    for(ll i=0;i<h;i++){
        for(ll j=0;j<w;j++){
            cin>>s[i][j];
        }
    }
    ll ans = 1;

    for(ll i=x+1;i<h;i++){
        if(s[i][y]=='#')break;
        ans++;
    }
    for(ll i=x-1;i>=0;i--){
        //cout<<i<<endl;
        if(s[i][y]=='#')break;
        ans++;
    }
    for(ll i=y-1;i>=0;i--){
        //cout<<i<<endl;
        if(s[x][i]=='#')break;
        ans++;
    }
    for(ll i=y+1;i<w;i++){
        if(s[x][i]=='#')break;
        ans++;
    }
    cout<<ans<<endl;
    //------------------------------
    //fclose(stdin);
    //fclose(stdout);
    //ll end_t=clock();cout<<"time="<<end_t-begin_t<<"ms"<<endl;
    //------------------------------- 
    return 0;
}
//----------------------------------------------------------------------






























#include<bits/stdc++.h>
#define db double
#define reg register
#define LL long long
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define ull unsigned long long
#define rep(i,a,b) for(int i=a,i##end=b;i<=i##end;++i)
#define drep(i,a,b) for(int i=a,i##end=b;i>=i##end;--i)
#define erep(i,a) for(int i=head[a];i;i=e[i].nxt)


using namespace std;
bool Handsome;
inline void Mi(int &x,int y){if(x>y && (x=y));}
inline void Mx(int &x,int y){if(x<y && (x=y));}
const int M=1005;
int n,m,ans=1e9;
bool vis[M][M];
vector<int> g[M][30];
struct node{int a,b,st;}tmp;
queue<node> q;
bool Most;
int main(){
//	printf("%.2lfMB\n",(&Most-&Handsome)/1024.0/1024.0);
	scanf("%d%d",&n,&m);
	rep(i,1,m){
		int a,b;char c;
		scanf("%d %d %c",&a,&b,&c);
		g[a][c-'a'].pb(b);
		g[b][c-'a'].pb(a);
	}
	vis[1][n]=1;
	q.push((node){1,n,0});
	while(!q.empty()){
		tmp=q.front();q.pop();
		int a=tmp.a,b=tmp.b,st=tmp.st;
		if(st>=ans)break;
		if(a==b){Mi(ans,st);continue;}
		rep(p,0,25){
			rep(i,0,g[a][p].size()-1)
				if(g[a][p][i]==b)Mi(ans,st+1);
			rep(i,0,g[b][p].size()-1)
				if(g[b][p][i]==a)Mi(ans,st+1);
			rep(i,0,g[a][p].size()-1){
				int u=g[a][p][i];
				rep(j,0,g[b][p].size()-1){
					int v=g[b][p][j];
					if(vis[u][v])continue;vis[u][v]=1;
					q.push((node){u,v,st+2});
				}
			}
		}
	}
	if(ans==1e9)ans=-1;
	printf("%d\n",ans);
	return 0;
}