#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC optimize("conserve-stack")
#include<bits/stdc++.h>
#define int long long
#define ll long long
#define down cout<<'\n';
#define debug cout<<" cucuucucuuu",down
#define NHP ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
#define modwwe int t;cin>>t; while(t--)
#define bit(i,j) (i>>j&1)
#define sobit(a) __builtin_popcountll(a)
#define task "test"
#define fin(x) freopen(x".inp","r",stdin)
#define fou(x) freopen(x".out","w",stdout)
#define pb push_back
#define mask(k) (1<<k)
#define mp make_pair
#define checktime cerr << (double)clock() / CLOCKS_PER_SEC * 1000 << " ms";
using namespace std;
#define getchar_unlocked getchar
inline int scan()
{
char c = getchar_unlocked();
int x = 0;
while (c < '0' || c > '9')
{
c = getchar_unlocked();
}
while (c >= '0' && c <= '9')
{
x = (x << 1) + (x << 3) + c - '0';
c = getchar_unlocked();
}
return x;
}
void phongbeo();
const int inf = 1e9;
const ll mod2 = 1e9 + 7;
const int mod1 = 998244353;
const ll base=67;
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
int add(int x,int y)
{
if(x+y>=mod2) x-=mod2;
if(x+y<0)x+=mod2;
return x+y;
}
struct icd
{
long double a;
int b;
};
struct ib
{
int a;
int b;
};
struct ic
{
int a, b, c;
};
struct id
{
int a, b, c, d;
};
struct ie
{
int a, b, c, d, e;
};
int n, m, s1, s2, s4, s3, sf, k, s5, s6, mx, s7, s8, s9, mx2, res, dem2 = 0, dem = 0, s33, dem3, dem4, mid, l2, r2, center;
int i, s10, s12,k1,k2,k3,s11,t,lim,w,l,r ;
int kk;
int el = 19;
main()
{
if(fopen(task".inp","r"))
{
fin(task);
fou(task);
}
NHP
/// cin>>s1;
// modwwe
phongbeo();
// checktime
}
bool cmp(ic a,ic b)
{
return a.c<b.c;
}
int query;
int dist[2001][2001];
int b[2001][2001];
bool a[2001][2001];
int st[18][200001];
int cost[18][200001];
int in[200001];
int ou[200001];
vector<ic> v;
vector<ib> ke[200001];
deque<id> p;
struct ds
{
ib dsu[200001];
void reset(int x)
{
dsu[x]= {1,x};
}
int get(int x)
{
if(dsu[x].b==x) return x;
return dsu[x].b=get(dsu[x].b);
}
bool noi(int x,int y)
{
x=get(x);
y=get(y);
if(x==y) return 0;
if(dsu[x].a<dsu[y].a) swap(x,y);
dsu[x].a+=dsu[y].a;
dsu[y].b=x;
return 1;
}
} ds;
void dfs(int x,int y)
{
st[0][x]=y;
in[x]=++dem;
for(auto f:ke[x])
if(f.a^y)
{
dfs(f.a,x);
cost[0][f.a]=f.b;
}
ou[x]=dem;
}
bool check(int x,int y)
{
if(in[x]<=in[y]&&in[y]<=ou[x]) return 1;
return 0;
}
int lca(int x,int y)
{
int s=0;
if(check(x,y)) return 0;
for(int i=17; i>=0; --i)
if(!check(st[i][x],y))
{
s=max(s,cost[i][x]);
x=st[i][x];
}
s=max(s,cost[0][x]);
return s;
}
int solve(int x,int y)
{
if(ds.get(x)!=ds.get(y)) return -1;
return max(lca(x,y),lca(y,x));
}
void phongbeo()
{
cin>>n>>m>>k>>query;
for(int i=1; i<=n; i++)
for(int j=1; j<=m; j++)
{
char x;
cin>>x;
if(x=='.') a[i][j]=1;
else a[i][j]=0;
}
for(int i=1; i<=k; i++)
{
ds.reset(i);
cin>>l>>r;
p.push_front({0,l,r,i});
}
while(!p.empty())
{
id x=p.front();
p.pop_front();
if(b[x.b][x.c]!=0) continue;
b[x.b][x.c]=x.d;
dist[x.b][x.c]=x.a;
for(int j=0; j<4; j++)
{
l2=x.b+dx[j];
r2=x.c+dy[j];
if(l2<=n&&l2>0&&r2<=m&&r2>0&&a[l2][r2]&&b[l2][r2]==0)
p.pb({x.a+1,l2,r2,x.d});
}
}
for(int i=1; i<=n; i++)
for(int j=1; j<=m; j++)
for(int f=0; f<4; f++)
{
l2=i+dx[f];
r2=j+dy[f];
if(l2<=n&&l2>0&&r2<=m&&r2>0&&b[l2][r2]!=b[i][j]&&min(b[i][j],b[l2][r2])!=0)
v.pb({b[l2][r2],b[i][j],dist[i][j]+dist[l2][r2]});
}
sort(v.begin(),v.end(),cmp);
for(auto x:v)
if(ds.noi(x.a,x.b))
{
ke[x.a].pb({x.b,x.c});
ke[x.b].pb({x.a,x.c});
}
for(int i=1; i<=k; i++)
if(!in[i])
{
dfs(i,0);
}
ou[0]=dem;
for(int i=1; i<18; i++)
for(int j=1; j<=k; j++)
{
st[i][j]=st[i-1][st[i-1][j]],
cost[i][j]=max(cost[i-1][j],cost[i-1][st[i-1][j]]);
}
while(query--)
{
cin>>l>>r;
cout<<solve(l,r),down
}
}
