func_code_string: #include <bits/stdc++.h>   #pragma GCC optimize(2)   using namespace std;   inline int read() {     int x = 0, w = 1;     char c = getchar();     while (c <  0  || c >  9 ) {       if (c ==  - ) w = -1;       c = getchar();     }     while (c <=  9  && c >=  0 ) {       x = (x << 1) + (x << 3) + c -  0 ;       c = getchar();     }     return w == 1 ? x : -x;   }   int n, cnt, tot, l[800005], r[800005], a[800005 << 1], lx[800005], rx[800005],       p[800005], t[800005], p2[800005], h[800005];   int main() {     int T = read();     while (T--) {       n = read();       cnt = 0;       tot = 0;       for (int i = 1; i <= n; i++) {         l[i] = read(), r[i] = read();         a[++cnt] = l[i], a[++cnt] = r[i];       }       sort(a + 1, a + cnt + 1);       tot = unique(a + 1, a + cnt + 1) - a - 1;       for (int i = 1; i <= n; i++) {         lx[i] = lower_bound(a + 1, a + tot + 1, l[i]) - a;         rx[i] = lower_bound(a + 1, a + tot + 1, r[i]) - a;         lx[i] <<= 1;         rx[i] <<= 1;       }       int tmp = 0;       for (int i = 1; i <= tot * 2; i++) p2[i] = 0, h[i] = 0, p[i] = 0;       for (int i = 1; i <= tot * 2; i++) t[i] = 0;       for (int i = 1; i <= n; i++) t[lx[i]]++, t[rx[i] + 1]--;       for (int i = 1; i <= tot * 2; i++) tmp += t[i], p[i] = tmp;       for (int i = 1; i <= tot * 2; i++)         if (p[i] != p[i - 1] && p[i] == 1) p2[i] = 1;       for (int i = 1; i <= tot * 2; i++) h[i] = h[i - 1] + p2[i];       int ans = -1e9, ans1 = 0;       for (int i = 1; i <= tot * 2 + 1; i++)         if (p[i] != 0 && p[i - 1] == 0) ans1++;       for (int i = 1; i <= n; i++) {         int q = h[rx[i]] - h[lx[i] - 1];         q -= (p[rx[i]] == 1), q -= (p[lx[i]] == 1);         ans = max(ans, q);       }       cout << ans1 + ans << endl;     }     return 0;   }   