Dij

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int,int>
#define vec vector
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvl(vector <ll> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}


void cvv(vector <vector <int> > &v){
    for (auto x: v) cv(x);
    cout<<"\n";
}

void cvb(vector <bool> v){
    for (bool x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvs(vector <string>  v){
    for (auto a: v){
        cout<<a<<"\n";
    }
}

void cvp(vector <pii> a){
    for (auto p: a){
        cout<<p.first<<' '<<p.second<<"\n";
    }
    cout<<"\n";
}

vector <vector <pii> > G;
vector <int> d;
int n,fr, to;

const int inf = 2e9;

void dij(){
    d[fr] = 0;
    set <pii> Q;
    for (auto p: G[fr]){
        Q.insert(p);
    }
    while (!Q.empty()){
        int v = Q.begin()->second;
        Q.erase(Q.begin());
        for (pii p: G[v]){
            int u = p.second, l = p.first;
            int newd = d[v] + l;
            if (newd < d[u]){
                Q.erase({u, d[u]});
                d[u] = newd;
                Q.insert({d[u], u});
            }
        }
    }
}

int main()
{
    ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>fr>>to;
	d.assign(n, inf);
	fr--;
	to--;

	G.resize(n);
	for (int i=0;i<n;++i){
        for (int j=0;j<n;++j){
            int l; cin>>l;
            if (l==-1 || i == j) continue;
            G[i].push_back({l, j});
        }
	}
	dij();
	cout<<d[to];
}