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#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int N;
vector<int> testcase;
vector<int> result;

int gcd(int a, int b){
    if(a%b == 0){
        return b;
    }
    
    return gcd(b, a%b);
}
void dfs(int num, int status){
    if(status == (1<<N)-1){
        result.push_back(num);
    }
    
    for(int i = 0; i<N; i++){
        if(!(status & (1<<i))){
            int next = num*10 + testcase[i];
            dfs(next, status | (1<<i));
        }
    }
}

int main(){

    scanf("%d", &N);
    
    
    for(int i = 0; i<N; i++){
        int tmp;
        scanf("%d", &tmp);
        testcase.push_back(tmp);
    }
    
    int K;
    scanf("%d", &K);
    

    for(int i = 0; i<N; i++){
        dfs(testcase[i], (1<<i));
    }
    
    sort(result.begin(), result.end());
    
    result.erase(unique(result.begin(), result.end()), result.end());
    
    int cnt = 0;
    for(int i = 0; i<result.size(); i++){
        if(result[i]%K == 0){
            cnt++;
        }
    }
    
    if(cnt == 0){
        printf("0/1\n");
    }
    else if(result.size() == cnt){
        printf("1/1\n");
    }
    else{
        int a = gcd((int)result.size(), cnt);
        
        printf("%d/%d\n", cnt/a, (int)result.size()/a);
    }
    
    
    
    
}

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