#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 5, MAXM = 5e3 + 5;
namespace fast_io {
char buf[1 << 12], *p1 = buf, *p2 = buf, sr[1 << 23], z[23], nc;
int C = -1, Z = 0, Bi = 0, ny;
inline char gc() {
  return p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1 << 12, stdin), p1 == p2)
             ? EOF
             : *p1++;
}
inline int read() {
  int x = 0;
  ny = 1;
  while (nc = gc(), (nc < 48 || nc > 57) && nc != EOF)
    if (nc == 45) ny = -1;
  Bi = 1;
  if (nc < 0) return nc;
  x = nc - 48;
  while (nc = gc(), 47 < nc && nc < 58 && nc != EOF)
    x = (x << 3) + (x << 1) + (nc ^ 48), Bi++;
  return x * ny;
}
inline double gf() {
  int a = read(), y = ny, b = (nc != '.') ? 0 : read();
  return (b ? a + (double)b / pow(10, Bi) * y : a);
}
inline int gs(char *s) {
  char c, *t = s;
  while (c = gc(), c <= 32)
    ;
  *s++ = c;
  while (c = gc(), c > 32) *s++ = c;
  return s - t;
}
inline void ot() {
  fwrite(sr, 1, C + 1, stdout);
  C = -1;
}
inline void flush() {
  if (C > 1 << 22) ot();
}
template <typename T>
inline void write(T x, char t) {
  int y = 0;
  if (x < 0) y = 1, x = -x;
  while (z[++Z] = x % 10 + 48, x /= 10)
    ;
  if (y) z[++Z] = '-';
  while (sr[++C] = z[Z], --Z)
    ;
  sr[++C] = t;
  flush();
}
inline void write(char *s) {
  int l = strlen(s);
  for (int i = 0; i < l; i++) sr[++C] = *s++;
  sr[++C] = '\n';
  flush();
}
}  // namespace fast_io
using namespace fast_io;
int n, m, st[20][MAXN], Lg[MAXN], stk[MAXM], top, fa[MAXM], Mx[MAXM];
double f[MAXM][MAXM], t1[MAXM], t2[MAXM], t3[MAXM], t4[MAXM], ans;
vector<int> G[MAXN];
struct Node {
  int l, r;
  double p;
} p[MAXM];
inline int Max(int l, int r) {
  int k = Lg[r - l + 1];
  return max(st[k][l], st[k][r - (1 << k) + 1]);
}
void Solve(int x) {
  int l = p[x].l, r = p[x].r, t = 0;
  Mx[x] = Max(l, r);
  for (auto y : G[x]) Solve(y);
  f[x][0] = 1;
  for (auto y : G[x]) {
    for (int i = 0; i <= m; i++) t1[i] = f[x][i], t2[i] = t3[i] = t4[i] = 0;
    double pp = p[y].p;
    for (int i = 0; i <= m; i++)
      t2[max(Mx[y] + i - Mx[x] + 1, 0)] += pp * f[y][i],
          t2[max(Mx[y] + i - Mx[x], 0)] += (1 - pp) * f[y][i];
    for (int i = 0; i <= m; i++)
      t3[i] = t3[i - 1] + t1[i], t4[i] = t4[i - 1] + t2[i];
    for (int i = 0; i <= m; i++)
      f[x][i] = t1[i] * t4[i] + t2[i] * t3[i] - t1[i] * t2[i];
  }
}
int main() {
  n = read(), m = read();
  for (int i = 1; i <= n; i++) st[0][i] = read();
  Lg[0] = -1;
  for (int i = 1; i <= n; i++) Lg[i] = Lg[i >> 1] + 1;
  for (int i = 1; i <= 19; i++)
    for (int j = 1; j <= n; j++)
      st[i][j] = max(st[i - 1][j], st[i - 1][j + (1 << i - 1)]);
  for (int i = 1; i <= m; i++) p[i].l = read(), p[i].r = read(), p[i].p = gf();
  sort(p + 1, p + m + 1,
       [](Node x, Node y) { return x.l == y.l ? x.r > y.r : x.l < y.l; });
  p[0].l = 1, p[0].r = n;
  for (int i = 1; i <= m; i++) {
    int l = p[i].l, r = p[i].r;
    for (; top && p[stk[top]].r < l; top--)
      ;
    fa[i] = stk[top], stk[++top] = i;
  }
  for (int i = 1; i <= m; i++) G[fa[i]].push_back(i);
  Solve(0);
  for (int i = 0; i <= m; i++) ans += f[0][i] * (Mx[0] + i);
  printf("%.10lf", ans);
  return 0;
}
