#include <complex>
#include <vector>
#include <set>
#include <cstdio>
using namespace std;
const double EPS = 1e-12;
typedef complex<long double> P;
struct L : public vector<P> {
L(const P &a, const P &b) {
push_back(a); push_back(b);
}
};
bool intersectSP(const L &s, const P &p) {
return abs(s[0]-p)+abs(s[1]-p)-abs(s[1]-s[0]) < EPS; // triangle inequality
}
long long pow_binary_mod(long long x,long long y,long long M){
long long z=1;
for(;y;y>>=1){
if((y&1)!=0)z=z*x%M;
x=x*x%M;
}
return z;
}
int main(){
int M=998244353;
int N,x,y;
scanf("%d",&N);
vector<P>v(N);
int r=pow_binary_mod(2,N,M);
set<L>se;
for(int i=0;i<N;i++)scanf("%d%d",&x,&y),v[i]={(double)x,(double)y};
for(int i=0;i<N;i++)for(int j=i+1;j<N;j++){
L l(v[i],v[j]);
int n=0;
for(int k=0;k<N;k++)if(k!=i&&k!=j&&intersectSP(l,v[k]))n++;
r=(r-pow_binary_mod(2,n,M))%M;
}
printf("%d\n",((r-N-1)%M+M)%M);
}
./Main.cpp: In function ‘int main()’:
./Main.cpp:31:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&N);
^
./Main.cpp:35:68: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
for(int i=0;i<N;i++)scanf("%d%d",&x,&y),v[i]={(double)x,(double)y};
^