180206_5014_스타트링크

//https://www.acmicpc.net/problem/5014 #include <iostream>

#include <queue>

using namespace std;

int BD[1000001];

int F,S,G,U,D;

int mn=10000003;

bool bfs(){

queue<int> q;

q.push(S);

BD[S]=1;

while(!q.empty()){

int now=q.front();

q.pop();

if(now==G){

if(mn>BD[now]) mn=BD[now];

return true;

}

int nu=now+U;

int nd=now-D;

if(nu>0 && nu<=F && !BD[nu]){

q.push(nu);

BD[nu]=BD[now]+1;

}

if(nd>0 && nd<=F && !BD[nd]){

q.push(nd);

BD[nd]=BD[now]+1;

}

}

return false;

}

int main(){

cin >> F >> S >> G >> U >> D;

if(bfs()) cout << mn-1;

else cout << "use the stairs";

return 0;

}