问题描述：火车分n小节，从头开始进站出站，有可能的顺序

#include<fstream>
#include<sstream>
#include<iostream>
#include<stack>

using namespace  std;

int main(){
	ifstream in("rail.txt");
	for(int n,line=0;in>>n&&n&&in.ignore();){
		cout<<(line++ ? "\n":"");
		for(string s;getline(in,s)&&s!="0";){
			istringstream sin(s);
			stack<int> st;
			for(int last=0,coach;sin>>coach;st.pop()){
				for(int p=last+1;p<=coach;++p) st.push(p);
				if(last<coach) last=coach;
				if(st.top()!=coach) break;
			}
			cout<<(!sin? "Yes\n":"No\n");
		}
	}
}

//rail.txt
5
3 2 1 5 4
5 4 1 2 3
0