Floyd-Warshall algorithm

#include <cstdio>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
    int n, i, j, k, vBegin, vEnd;
    scanf("%d", &n);
    vector < vector <int> > arr(n, vector <int> (n));
    const int MISS = (n * (n - 1)) / 2 + 1;
    for(i = 0; i < n; i++)
    {
        for(j = 0; j < n; j++)
        {
            scanf("%d", &arr[i][j]);
            if(!arr[i][j] && i != j) arr[i][j] = MISS;
        }
    }
    for(k = 0; k < n; k++) for(i = 0; i < n; i++) for(j = 0; j < n; j++) arr[i][j] = min(arr[i][j], arr[i][k] + arr[k][j]);
    scanf("%d%d", &vBegin, &vEnd);
    vBegin--, vEnd--;
    if(arr[vBegin][vEnd] == MISS) printf("-1");
    else printf("%d", arr[vBegin][vEnd]);
    return 0;
}