#include <map>
#include <cmath>
#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define F(i,j,k) for (int i=j;i<=k;++i)
#define D(i,j,k) for (int i=j;i>=k;--i)
#define ll long long
#define mp make_pairnamespace Subtask1{const int p=1000003;ll fac[p],inv[p];void Shaker(){int i;for (fac[0]=1,i=1;i<p;++i)fac[i]=fac[i-1]*i%p;for (inv[1]=1,i=2;i<p;++i)inv[i]=(p-p/i)*inv[p%i]%p;for (inv[0]=1,i=1;i<p;++i)(inv[i]*=inv[i-1])%=p;}ll C(ll n,ll m){if (n<m) return 0;if (n<p&&m<p) return fac[n]*inv[m]*inv[n-m]%p;return C(n%p,m%p)*C(n/p,m/p)%p;}
}namespace Subtask2{const int p=1019663265;int pri[]={3,5,6793,10007};ll fac[4][10007],inv[4][10007],k1=339887755,k2=407865306,k3=673070820,k4=618502650;void Shaker(){int i,j;for (j=0;j<4;++j){int np=pri[j];for (fac[j][0]=1,i=1;i<np;++i)fac[j][i]=fac[j][i-1]*i%np;for (inv[j][1]=1,i=2;i<np;++i)inv[j][i]=(np-np/i)*inv[j][np%i]%np;for (inv[j][0]=1,i=1;i<np;++i)(inv[j][i]*=inv[j][i-1])%=np;}}ll C(ll n,ll m,int j){int np=pri[j];if (n<m) return 0;if (n<np&&m<np) return fac[j][n]*inv[j][m]*inv[j][n-m]%np;return C(n%np,m%np,j)*C(n/np,m/np,j)%np;}ll C(ll n,ll m){ll r1=C(n,m,0),r2=C(n,m,1),r3=C(n,m,2),r4=C(n,m,3);return (r1*k1+r2*k2+r3*k3+r4*k4)%p;}
}struct Point{ll x,y;void read(){scanf("%lld%lld",&x,&y);}
}points[220];bool cmp(Point a,Point b)
{return a.x==b.x?a.y<b.y:a.x<b.x;}ll ksm(ll a,ll b,ll p)
{ll ret=1;for (;b;b>>=1,(a*=a)%=p)if (b&1) (ret*=a)%=p;return ret;
}ll f[220],t,n,m;void solve1()
{using namespace Subtask1;Shaker();F(i,1,t){f[i]=C(points[i].x+points[i].y,points[i].x);F(j,1,i-1) if (points[j].y<=points[i].y){(f[i]-=f[j]*C(points[i].x-points[j].x+points[i].y-points[j].y,points[i].x-points[j].x)%p);f[i]+=p; f[t]%=p;}}
}void solve2()
{using namespace Subtask2;Shaker();F(i,1,t){f[i]=C(points[i].x+points[i].y,points[i].x);F(j,1,i-1) if (points[j].y<=points[i].y){(f[i]-=f[j]*C(points[i].x-points[j].x+points[i].y-points[j].y,points[i].x-points[j].x)%p);f[i]%=p;f[i]+=p; f[t]%=p;}}
}void Finout()
{freopen("in.txt","r",stdin);freopen("wa.txt","w",stdout);
}int main()
{ll p;scanf("%lld%lld%lld%lld",&n,&m,&t,&p);F(i,1,t) points[i].read();++t;points[t].x=n;points[t].y=m;sort(points+1,points+t+1,cmp);if (p==1000003) solve1(); else solve2();cout<<f[t]<<endl;
}