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 <iostream>
#include <vector>
#include <string>
#include <cstdlib>
#include <cmath>
using namespace std;

vector<string> split(const string &str, char delim){
  vector<string> res;
  size_t current = 0, found;
  while((found = str.find_first_of(delim, current)) != string::npos){
    res.push_back(string(str, current, found - current));
    current = found + 1;
  }
  res.push_back(string(str, current, str.size() - current));
  return res;
}

double isCross(double p1_x,double p1_y,double p2_x,double p2_y,double p3_x,double p3_y,double p4_x,double p4_y){  
    return ( (p1_x-p2_x)*(p3_y-p1_y) + (p1_y-p2_y)*(p1_x-p3_x)) * ((p1_x-p2_x)*(p4_y-p1_y) + (p1_y-p2_y)*(p1_x-p4_x));  
}




int main()
{
	string s;
	while(cin >> s)
	{
		vector<string> _s = split(s,',');
		double *a = new double[8];
		for(int i=0;i<8;i++)
		{
			a[i] = atoi(_s[i].c_str());
		}

		if(isCross(a[0],a[1],a[4],a[5],a[2],a[3],a[6],a[7]) > 0.0 || isCross(a[2],a[3],a[6],a[7],a[0],a[1],a[4],a[5]) > 0.0)
		{
			cout << "NO" << endl; 
		}
		else
		{
			cout << "YES" << endl;
		}
	}

	return 0;
}

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;
}