func_code_string: #include <bits/stdc++.h>   using namespace std;   void err(istream_iterator<string> it) { cerr << endl; }   template <typename T, typename... Args>   void err(istream_iterator<string> it, T a, Args... args) {     cerr << *it <<   =   << a <<   ,  ;     err(++it, args...);   }   namespace fastIO {   bool IOerror = 0;   inline char nc() {     static char buf[100000], *p1 = buf + 100000, *pend = buf + 100000;     if (p1 == pend) {       p1 = buf;       pend = buf + fread(buf, 1, 100000, stdin);       if (pend == p1) {         IOerror = 1;         return -1;       }     }     return *p1++;   }   inline bool blank(char ch) {     return ch ==     || ch ==   n  || ch ==   r  || ch ==   t ;   }   inline void read(int &x) {     char ch;     while (blank(ch = nc()))       ;     if (IOerror) return;     for (x = ch -  0 ; (ch = nc()) >=  0  && ch <=  9 ; x = x * 10 + ch -  0 )       ;   }   }  // namespace fastIO   using namespace fastIO;   const double PI = acos(-1.0);   const double eps = 1e-8;   const int mod = 1e9 + 7;   long long qp(long long b, long long n) {     long long r = 1;     if (n < 0) n += mod - 1;     b %= mod;     for (; n; n >>= 1, b = b * b % mod)       if (n & 1) r = r * b % mod;     return r;   }   int sgn(double x) {     if (x < -eps) return -1;     return x > eps ? 1 : 0;   }   const int maxn = 3e5 + 7;   const int N = 1e5 + 10;   int n;   int sum[N], dif[N], a[N];   pair<int, int> p[N];   int main() {     scanf( %d , &n);     long long ans = 0;     for (int i = 1; i <= n; ++i) {       scanf( %d , &a[i]);       sum[a[i]]++;       ans += (1LL * a[i] * (n - a[i] + 1));     }     for (int i = 1; i <= n; ++i) sum[i] += sum[i - 1];     for (int i = 1; i < n; ++i) {       p[i].first = a[i];       p[i].second = a[i + 1];       if (p[i].first > p[i].second) swap(p[i].first, p[i].second);       ans -= 1LL * p[i].first * (n - p[i].second + 1);     }     printf( %lld n , ans);   }   