#include "network.h"
#include <bits/stdc++.h>
using namespace std;
const int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1};
#define OVL(x,s) for(auto y:x) cout<<y<<s; cout<<"\n";
#ifdef IOI
void dbg_out() { cout << endl; }
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cout << ' ' << H; dbg_out(T...); }
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__);
#else
#define dbg(...) 1337;
#endif
#define endl "\n"
#define pb push_back
#define F first
#define S second
#define ll long long
#define mod 1000000007
#define all(v) v.begin(),v.end()
vector<int> path;
int n;
int c;
void solve(int l,int r,int m,int i){
dbg(l,r,m,i)
if(l==r){
return;
}
for(int i=1;i<=n;i++){
if(i==l||i==r) continue;
int x=ping(l,i);
int y=ping(i,r);
dbg(x,y,c,m)
if(x+y+1==m){
path[m]=i;
solve(l,i,m/2,m/2);
solve(i,r,m/2,m+m/2);
}
}
}
void findRoute (int N, int a, int b)
{
/*
* Obviously, this is not a good solution.
* Replace it with your own code.
*/
n=N;
c=ping(a,b);
path.resize(c+1,0);
solve(a,b,(c+1)/2,c/2);
for(auto x:path){
dbg(x)
if(x==0) continue;
travelTo(x);
}
travelTo(b);
}
#ifdef IOI
#include <cstdio>
#include <cstdlib>
#include "network.h"
static const int MAX_N = 1010;
static int N, a, b, M,
pingCount,
routeLength, current;
static int di[MAX_N][MAX_N];
static void raiseError (const char* message)
{
printf ("ERROR\n%s\n", message);
exit (0);
}
int ping (int i, int j)
{
if (i < 1 || j < 1 || i > N || j > N || i == j)
raiseError ("ping called with invalid arguments");
++pingCount;
if (pingCount > M)
raiseError ("Too many calls to ping");
return di[i-1][j-1];
}
void travelTo (int k)
{
if (k < 1 || k > N)
raiseError ("travelTo called with invalid argument");
if (k == current || di[current-1][k-1] > 0)
raiseError ("Travelling to nonadjacent computer");
++routeLength;
if (routeLength > di[a-1][b-1] + 1)
raiseError ("Route is too long");
current = k;
}
int main()
{
scanf ("%d%d%d%d", &N, &a, &b, &M);
for (int u = 0; u < N; ++u)
for (int v = 0; v < N; ++v)
scanf("%d", &di[u][v]);
pingCount = 0;
routeLength = 0;
current = a;
findRoute (N, a, b);
if (current != b)
raiseError ("Message has not reached its target");
if (routeLength < di[a-1][b-1] + 1)
raiseError ("Unexpected: route is too short");
printf ("OK\n");
return 0;
}
#endif
