#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------

int N;
ll X[201],Y[202];
const ll mo=998244353;

ll hoge(int a,int b,int c) {
	ll bx=X[b]-X[a];
	ll by=Y[b]-Y[a];
	ll cx=X[c]-X[a];
	ll cy=Y[c]-Y[a];
	ll s=abs(bx*cy-cx*by);
	return s%mo;
}


void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N;
	FOR(i,N) {
		cin>>X[i]>>Y[i];
		X[i+N]=X[i];
		Y[i+N]=Y[i];
	}
	ll S=0;
	for(i=1;i<N-1;i++) (S+=hoge(0,i,i+1))%=mo;
	cout<<S*(mo+1)/2%mo<<endl;
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}