func_code_string: #include <bits/stdc++.h>   #pragma GCC optimize( Ofast )   const long long INF = 1e9 + 7;   const long long maxn = 2e5 + 7;   using namespace std;   void solve() {     long long a, b, c, d;     cin >> a >> b >> c >> d;     long long ans = 0;     for (long long z = c; z < d + 1; z++) {       long long r1 = z - c + 1;       long long r2 = z - b + 1;       if (r1 > b) continue;       long long sStart = 1;       if (r2 < b) {         sStart += (b - r2);       }       r2 = max(r2, b);       long long numTerms = c - r2 + 1;       long long whichTermGreater = b - a + 2 - sStart;       long long numGreater = max(min(numTerms - whichTermGreater, numTerms), 0LL);       ans += numGreater * (b - a + 1);       numTerms -= numGreater;       long long finalTerm = sStart + numTerms - 1;       long long summn = (numTerms) * (sStart + finalTerm);       summn /= 2;       ans += summn;     }     cout << ans <<   n ;   }   int main(int argc, char** argv) {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     int T = 1;     while (T--) {       solve();     }     return 0;   }   