DFS

#include<iostream>
using namespace std;
char a[20][10]={{},{},{'a','b','c'},{'d','e','f'},{'g','h','i'},{'j','k','l'},{'m','n','o'},{'p','q','r','s'},{'t','u','v'},{'w','x','y','z'}};
bool mark[20][10];
char ans[125];
int maxn[10]={0,0,3,3,3,3,3,4,3,4};
int c[10];
int n;
void dfs(int dep){
	if(dep>=n){
		for(int i=0; i<n; i++)	cout<<ans[i];
		cout<<endl;
		return;
	}
	for(int i=0; i<maxn[c[dep]]; i++){
		mark[c[dep]][i]=1;
		ans[dep]=a[c[dep]][i];
		dfs(dep+1);
		mark[c[dep]][i]=0;
	}
}
int main(){
	cin>>n;
	int cnt=1;
	for(int i=0; i<n; i++){
		cin>>c[i];
		cnt*=maxn[c[i]];
	}
	cout<<cnt<<endl;
	dfs(0);
	return 0;
}