阅读程序写结果：
#include <iostream>using namespace std;int fun(int n){if(n == 1)return 1;if(n == 2)return 2;return fun(n -2) - fun(n - 1);}int main(){int n;cin >> n;cout << fun(n) << endl; return 0;}输入：7 输出：__
阅读程序写结果：
#include <iostream>using namespace std;int fun(int n){if(n == 1)return 1;if(n == 2)return 2;return fun(n -2) - fun(n - 1);}int main(){int n;cin >> n;cout << fun(n) << endl; return 0;}输入：7 输出：__