usaco 2.3.3: zero sum（暴搜）

ID: zhanghu15
TASK: zerosum
LANG: C++14
*/


#include <fstream>
#include <sstream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cmath>

using namespace std;
typedef long long int LL;

ofstream ("zerosum.out");
ifstream fin("zerosum.in");

int N;
char signs[10];

void dfs(int depth) {
    if (depth == N - 1) {
        LL sum = 0, cur = 1;
        int s = 1;  // sign
        for (int i = 0; i < depth; i++) {
            if (signs[i] == ' ') cur = cur * 10 + (i + 2);
            else if (signs[i] == '+') {
                sum += cur * s;
                s = 1;
                cur = i + 2;
            }
            else {
                sum += cur * s;
                s = -1;
                cur = i + 2;
            }
        }
        sum += cur * s;
        if (sum == 0) {
            fout << 1;
            for (int i = 0; i < depth; i++)
                fout << signs[i] << (i + 2);
            fout << endl;
        }
        return;
    }
    signs[depth] = ' ';
    dfs(depth + 1);
    signs[depth] = '+';
    dfs(depth + 1);
    signs[depth] = '-';
    dfs(depth + 1);
}

int main() {
    fin >> N;
    dfs(0);
    return 0;
}