#include <iostream> using namespace std; #define I int #define LL long long void count(); int main() { count(); return 0; } void count() { //小红的正整数计数 I l, r, t = 0; cin >> l >> r; t = (r - l + 1) % 2; if (t == 0) cout << (r - l + 1) / 2; else if (r % 2 == 0) cout << (r - l + 1) / 2 + 1; else cout << (r - l + 1) / 2; }