Go: package main

import (
	"bufio"
	"os"
	"strings"
	"strconv"
	"fmt"
)

func check(x, y, x1, y1, x2, y2 float64) float64 {
	return (x2-x1)*y - (y2-y1)*x + x1*y2 - x2*y1
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	a := make([]float64, 8)
	for scanner.Scan() {
		info := strings.Split(scanner.Text(), ",")
		for j := 0; j < 8; j++ {
			a[j], _ = strconv.ParseFloat(info[j], 64)
		}
		if check(a[0], a[1], a[2],a[3], a[6], a[7])*check(a[4], a[5], a[2], a[3], a[6], a[7]) < 0 && check(a[6], a[7], a[0], a[1], a[4], a[5])*check(a[2],a[3], a[0], a[1], a[4], a[5]) < 0 {
			fmt.Println("YES")	
		} else {
			fmt.Println("NO")
		}
	}
}

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i, s, n) for(int i = s; i < (int)n; i++)
#define per(i, n) for(int i = n; i >= 0; i--)
#define ROF(i, s, n) for(int i = s; i >= (int)n; i--)
#define FORIT(i, A) for (auto i : A)
#define PRINT(x) cout << (x) << "\n"
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define MP make_pair
#define EACH(i, n) for (__typeof((n).begin()) i = (n).begin(); i != (n).end(); ++i)
#define SZ(a) int((a).size())
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define CLR(a) memset((a), 0 ,sizeof(a))
#define NCLR(a) memset((a), -1 ,sizeof(a))
#define dump(x) cout << #x << " = " << (x) << "\n";
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << "\n";
#define sq(n) (n) * (n)
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef priority_queue<int> maxpq;
typedef priority_queue< int, vector<int>, greater<int> > minpq;
typedef complex<double> P;
static const double EPS = 1e-10;
static const double PI = acos( -1.0 );
static const int mod = 1000000007;
static const int INF = 1 << 30;
static const LL LL_INF = 1152921504606846976;
static const int dx[] = { -1, 0, 1, 0, 1, -1, 1, -1 };
static const int dy[] = { 0, -1, 0, 1, 1, 1, -1, -1 };

bool collision_detection( double x1, double y1, double x2, double y2, double x3, double y3, double xp, double yp ) {
	x2 -= x1;
	x3 -= x1;
	xp -= x1;
	y2 -= y1;
	y3 -= y1;
	yp -= y1;
	double t_size = fabs( ( x2 * y3 - y2 * x3 ) / 2 );
	t_size -= fabs( ( x2 * yp -  y2 * xp ) / 2 );
	t_size -= fabs( ( x3 * yp -  y3 * xp ) / 2 );
	x2 -= xp;
	x3 -= xp;
	y2 -= yp;
	y3 -= yp;
	yp = xp = 0;
	t_size -= fabs( ( x2 * y3 - y2 * x3 ) / 2 );
	return fabs( t_size ) < 1e-10;
}

int main() {
	double x[ 4 ], y[ 4 ];
	while ( ~scanf( "%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf", &x[ 0 ], &y[ 0 ], &x[ 1 ], &y[ 1 ], &x[ 2 ], &y[ 2 ], &x[ 3 ], &y[ 3 ] ) ) {
		bool print_yes = true;
		for ( int i = 0; i < 4; i++ ) {
			if ( collision_detection( x[ ( i + 1 ) % 4 ], y[ ( i + 1 ) % 4 ], x[ ( i + 2 ) % 4 ], y[ ( i + 2 ) % 4 ], x[ ( i + 3 ) % 4 ], y[ ( i + 3 ) % 4 ], x[ i ], y[ i ] ) ) {
				print_yes = false;
				break;
			}
		}
		printf( "%s\n", !print_yes ? "YES" : "NO" );
	}
	return 0;
}

C++: #include <iostream>
#include <string>
#include <cmath>

using namespace std;

double sinvalue( double v1x, double v1y, double v2x, double v2y )
{

	return ( v1x*v2y - v1y * v2x ) / sqrt( v1x * v1x + v1y * v1y ) * sqrt( v2x * v2x + v2y * v2y );
}


int main()
{
	double ax, ay, bx, by, cx, cy, dx, dy;
	double vecx_ab, vecy_ab, vecx_bc, vecy_bc, vecx_cd, vecy_cd, vecx_da, vecy_da;
	double sindab, sinabc, sinbcd, sincda;
	char tmp;
	while ( cin >> ax >> tmp >> ay >> tmp >> bx >> tmp >> by >> tmp >> cx >> tmp >> cy >> tmp >> dx >> tmp >> dy )
	{
		vecx_ab = bx - ax; vecy_ab = by - ay;
		vecx_bc = cx - bx; vecy_bc = cy - by;
		vecx_cd = dx - cy; vecy_cd = dy - cy;
		vecx_da = ax - dy; vecy_da = ay - dy;

		sindab = sinvalue( vecx_ab, vecy_ab, -vecx_da, -vecy_da );
		sinabc = sinvalue( vecx_bc, vecy_bc, -vecx_ab, -vecy_ab );
		sinbcd = sinvalue( vecx_cd, vecy_cd, -vecx_bc, -vecy_bc );
		sincda = sinvalue( vecx_da, vecy_da, -vecx_cd, -vecy_cd );

		if ( sindab > 0 && sinabc > 0 && sinbcd > 0 && sincda > 0 )
		{
			cout << "YES" << endl;
		}
		else 
		{
			cout << "NO" << endl;
		}
	}

	return 0;
}

C++: #include <stdio.h>
#include <iostream>
#include <vector>
#include <list>
#include <cmath>
#include <fstream>
#include <algorithm>
#include <string>
#include <queue>
#include <set>
#include <map>
#include <complex>
#include <iterator>
#include <cstdlib>
#include <sstream>

using namespace std;

#define EPS (1e-10)
#define EQ(a,b) (abs((a) - (b)) < EPS)
#define EQV(a,b) (EQ((a).real(),(b).real()) && EQ((a).imag(),(b).imag()))

typedef complex<double> P;
typedef long long ll;

const int MAX_SIZE = 10000;

double dot(P a, P b) {
  return (a.real() * b.real() + a.imag() * b.imag());
}
double cross(P a, P b) {
  return (a.real() * b.imag() - a.imag() * b.real());
}
using namespace std;

int main(){

	double x[4];
	double y[4];
	char cm;
	while(cin>>x[0]){
		cin>>cm;
		cin>>y[0];
		for(int i = 1; i < 4; i++){
			cin>>cm>>x[i]>>cm>>y[i];
		}
		// ツつサツづェツつシツづェツづ個角ツづ個角ツ度ツづーツ計ツ算ツつオツ、180ツ度ツづーツ越ツつヲツづゥツ角ツ度ツつェツ堕カツ催敖つキツづェツづ篠、ツつュツづ堋づアツづつ「ツづゥ
		P A1(x[1]-x[0],y[1]-y[0]);
		P A2(x[3]-x[0],y[3]-y[0]);
		P B1(x[2]-x[1],y[2]-y[1]);
		P B2(x[0]-x[1],y[0]-y[1]);
		P C1(x[3]-x[2],y[3]-y[2]);
		P C2(x[1]-x[2],y[1]-y[2]);
		P D1(x[0]-x[3],y[0]-y[3]);
		P D2(x[2]-x[3],y[2]-y[3]);
		double t1=cross(A1,A2);
		double t2=cross(B1,B2);
		double t3=cross(C1,C2);
		double t4=cross(D1,D2);
		if(cross(A1,A2)<0||cross(B1,B2)<0||cross(C1,C2)<0||cross(D1,D2)<0){
			cout<<"NO"<<endl;
		}
		else
			cout<<"YES"<<endl;
	}

	return 0;
}