#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define _GLIBCXX_DEBUG
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=2167167167167167167;
const int INF=2100000000;
const ll mod=998244353;
#define rep(i,a) for (ll i=0;i<a;i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"Yes\n"; else cout<<"No\n";}
template<class T> void vec_out(vector<T> &p){for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}


void solve();
// oddloop
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t=1;
	//cin>>t;
	rep(i,t) solve();
}

void solve(){
	int H,W;
    cin>>H>>W;
    vector<string> S(H);
    rep(i,H) cin>>S[i];
    set<pair<int,int>> s;
    rep(i,H-1){
        int A=0,B=0;
        rep(j,W){
            if(S[i][j]!=S[i+1][j]) A++;
            else B++;
        }
        if(B==0) continue;
        if(A==0) s.insert({1,i+1});
        else{
            yneos(0);
            return ;
        }
    }
    rep(j,W-1){
        int A=0,B=0;
        rep(i,H){
            if(S[i][j]!=S[i][j+1]) A++;
            else B++;
        }
        if(B==0) continue;
        if(A==0) s.insert({2,j+1});
        else{
            yneos(0);
            return;
        }
    }
    int Q;
    cin>>Q;
    rep(i,Q){
        int a,b;
        cin>>a>>b;
        s.erase({a,b});
    }
    yneos(s.empty());
}