func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 2e5 + 10;   unsigned long long preLef[N], preRig[N], sum[N], a[N];   map<unsigned long long, unsigned long long> f, g;   int n, m;   unsigned long long Rand() {     return (unsigned long long)rand() * rand() * rand() +            (unsigned long long)rand() * rand() * rand();   }   int main() {     srand(time(0));     scanf( %d%d , &n, &m);     for (int i = 0, l, r; i < n; ++i) {       scanf( %d%d , &l, &r);       unsigned long long t = Rand();       a[l] ^= t;       a[r + 1] ^= t;       preLef[l] ^= t;       preRig[r] ^= t;     }     for (int i = 1; i <= m + 1; ++i) {       a[i] ^= a[i - 1];       sum[i] = sum[i - 1] ^ a[i];       preLef[i] ^= preLef[i - 1];       preRig[i] ^= preRig[i - 1];     }     g[0] = 0;     f[0] = 1;     unsigned long long ans = 0;     for (int i = 1; i <= m; ++i) {       unsigned long long t = sum[i] ^ preLef[i];       ans += f[t] * i - g[t];       t = sum[i] ^ preRig[i];       g[t] += i;       ++f[t];     }     for (int i = 1, lf = 0; i <= m; ++i)       if (!a[i])         ans -= (unsigned long long)(i - lf + 1) * (i - lf) / 2;       else         lf = i;     cout << ans << endl;     return 0;   }   