#include <stdio.h>
#include <math.h>
#include <vector>
typedef long long i64;
int rd()
{
    int k = 0, f = 1;
    char c = getchar();
    while (c < '0' || c > '9')
    {
        if (c == '-')
            f = 0;
        c = getchar();
    }
    while (c >= '0' && c <= '9')
    {
        k = (k << 1) + (k << 3) + (c ^ '0');
        c = getchar();
    }
    return f ? k : -k;
}
struct point
{
    int x, y;
    int idx;
    point(int _x = 0, int _y = 0, int id = 0) : x(_x), y(_y), idx(id) {}
    void input() { x = rd(), y = rd(); }
    point operator-(const point &o) const { return point(x - o.x, y - o.y); }
    // point product of vector
    i64 operator*(const point & o) const { return 1ll * x * o.x + 1ll * y * o.y; }
    // cross product of vector
    i64 operator^(const point &o) const { return 1ll * x * o.y - 1ll * y * o.x; }
    bool operator<(const point &o) const { return (x ^ o.x) ? (x < o.x) : (y < o.y); }
    bool operator==(const point &o) const { return (x == o.x) && (y == o.y); }    
};
bool isconvex(const std::vector<point>& pts)
{
    int n = (int) pts.size();
    if (n <= 2)
        return false;
    i64 cross = (pts[0] - pts[n - 1]) ^ (pts[n - 1] - pts[n - 2]);
    if (cross == 0)
        return false;
    bool dir = cross > 0;
    cross = (pts[1] - pts[0]) ^ (pts[0] - pts[n - 1]);
    if ((cross == 0) || ((cross > 0) != dir))
        return false;
    for (int i = 2; i < n; ++i)
    {
        cross = (pts[i] - pts[i - 1]) ^ (pts[i - 1] - pts[i - 2]);
        if ((cross == 0) || ((cross > 0) != dir))
            return false;
    }
    return true;
}
int main()
{
    int n = rd();
    std::vector<point> pts(n);
    for (int i = 0; i < n; ++i)
        pts[i].x = rd(), pts[i].y = rd();
    puts(isconvex(pts) ? "Yes" : "No");
}