Elevator Trouble

input/code.cpp: In function 'int main()':
input/code.cpp:28:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i=0; i<dfs.size(); ++i){
                            ^

#include <iostream>
#include <vector>
using namespace std;
const int INF=1222333444;

int f, s, g, u, d;


int dp[1222333];


vector<int> dfs;

inline int down(int c){
  return c-d>=1?c-d:c;
}
inline int up(int c){
  return c+u<=f?c+u:c;
}

int main(){
  for (int i=0; i<1222333; ++i) dp[i]=INF;
  
  cin >> f >> s >> g >> u >> d;
  
  dp[s]=0;
  dfs.push_back(s);
  for (int i=0; i<dfs.size(); ++i){
    int c=dfs[i];
    int gu=up(c);
    if (dp[gu]==INF){
      dp[gu]=dp[c]+1;
      dfs.push_back(gu);
    }
    int gd=down(c);
    if (dp[gd]==INF){
      dp[gd]=dp[c]+1;
      dfs.push_back(gd);
    }
  }
  if (dp[g]==INF) cout << "use the stairs\n";
  else cout << dp[g] << "\n";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED