#include using namespace std; int main() { int n; cin >> n; vector vec; for (int i = 0; i < n; i++) { int c; cin >> c; vec.push_back(c); } int count = 0; for (int i = 0; i < n - 1; i++) { for (int j = i + 1; j < n; j++) { if (abs(vec[i] - vec[j]) == 1) { count++; } } } cout << count << endl; return 0; }