If WA 37 then add this code( check: if there exist equal points ):
//////////////////////
void no(){
    puts("NO");
    exit(0);
}
//////////////////////
inline bool equal_lf( const double x, const double y ){
    return fabs(x-y)<=EPS;
    return fabs(x-y) <= EPS*max( fabs(x),fabs(y) );
}

//////////////////////
int main(){
///////////lalalalalalalal

    for( short i = 0; i < n; ++i ){
        for( short j = i+1; j < n; ++j ){
            if( equal_lf(p[i].x,p[j].x) && equal_lf(p[i].y,p[j].y) ) no();
        }
    }