#pragma GCC optimize("O3") #pragma GCC optimize(2) #pragma GCC optimize(3) #pragma GCC optimize("Ofast") #pragma GCC optimize("inline") #pragma GCC optimize("-fgcse") #pragma GCC optimize("-fgcse-lm") #pragma GCC optimize("-fipa-sra") #pragma GCC optimize("-ftree-pre") #pragma GCC optimize("-ftree-vrp") #pragma GCC optimize("-fpeephole2") #pragma GCC optimize("-ffast-math") #pragma GCC optimize("-fsched-spec") #pragma GCC optimize("unroll-loops") #pragma GCC optimize("-falign-jumps") #pragma GCC optimize("-falign-loops") #pragma GCC optimize("-falign-labels") #pragma GCC optimize("-fdevirtualize") #pragma GCC optimize("-fcaller-saves") #pragma GCC optimize("-fcrossjumping") #pragma GCC optimize("-fthread-jumps") #pragma GCC optimize("-funroll-loops") #pragma GCC optimize("-freorder-blocks") #pragma GCC optimize("-fschedule-insns") #pragma GCC optimize("inline-functions") #pragma GCC optimize("-ftree-tail-merge") #pragma GCC optimize("-fschedule-insnS2") #pragma GCC optimize("-fstrict-aliasing") #pragma GCC optimize("-falign-functions") #pragma GCC optimize("-fcse-follow-jumps") #pragma GCC optimize("-fsched-interblock") #pragma GCC optimize("-fpartial-inlining") #pragma GCC optimize("no-stack-protector") #pragma GCC optimize("-freorder-functions") #pragma GCC optimize("-findirect-inlining") #pragma GCC optimize("-fhoist-adjacent-loads") #pragma GCC optimize("-frerun-cse-after-loop") #pragma GCC optimize("inline-small-functions") #pragma GCC optimize("-finline-small-functions") #pragma GCC optimize("-ftree-switch-conversion") #pragma GCC optimize("-foptimize-sibling-calls") #pragma GCC optimize("-fexpensive-optimizations") #pragma GCC optimize("inline-functions-called-once") #pragma GCC optimize("-fdelete-null-Pointer-checks") #pragma GCC optimize("Ofast") #include #include #include #include #include #include #include #include #include #include #include using namespace std; long long int n,m,k,s,t,u,v; bool e[5001][5001]; long long int dp[5001][2][2]; int main() { cin.tie(0); ios::sync_with_stdio(false); cin >> n >> m >> k >> s >> t; for(int i=0;i> u >> v; e[u][v] = true; e[v][u] = true; } memset(dp,-1,sizeof(dp)); dp[s][0][0] = 0; queue >> que; que.push(make_pair(s,make_pair(0,0))); while(!que.empty()) { int now = que.front().first; int p = que.front().second.first; int f = que.front().second.second; que.pop(); for(int next=1;next<=n;next++) { if(next==now) continue; if(e[now][next]) { if(dp[next][(1-p)][f]==-1) { dp[next][(1-p)][f] = dp[now][p][f] + 1; que.push(make_pair(next,make_pair(1-p,f))); } } else { if(f==0) { if(dp[next][(1-p)][1]==-1) { dp[next][(1-p)][1] = dp[now][p][f] + 1; que.push(make_pair(next,make_pair(1-p,1))); } } } } } long long int res = 2e18; if(dp[t][k%2][0]!=-1) res = min(res,dp[t][k%2][0]); if(dp[t][k%2][1]!=-1) res = min(res,dp[t][k%2][1]); if(res <= k) cout << "Yes" << '\n'; else cout << "No" << '\n'; return 0; }