Lines

#include <bits/stdc++.h>

using namespace std;

int n, a[250][250], b[250][250], i, j, ma = 1e9, x, y, x1, x2, y1, y2, dx[4] = {0,1,0,-1}, dy[4] = {1,0,-1,0}, i1, j1;

char a1[251][251];

vector<pair<int, int>> q;

main() {
    for( cin >> n; i<n; ++i )
        for( j=0; j<n; ++j ) {
            cin >> a1[i][j];
            if( a1[i][j] == 'X' )
                a[i][j] = ma,
                x1 = i,
                y1 = j;
            if( a1[i][j] == 'O' )
                a[i][j] = -1;
            if( a1[i][j] == '@' )
                a[i][j] = 0,
                x2 = i,
                y2 = j;
            if( a1[i][j] == '.' )
                a[i][j] = ma;
        }
    q.push_back( { x2, y2 } );
    for( i=0; i<q.size(); ++i ) {
        x = q[i].first;
        y = q[i].second;
        for( j=0; j<4; ++j ) {
            int tx = x + dx[j];
            int ty = y + dy[j];
            if( tx < 0 || tx >= n || ty < 0 || ty >= n )
                continue;
            if( a[tx][ty] > a[x][y] + 1 )
                b[tx][ty] = j,
                a[tx][ty] = a[x][y] + 1,
                q.push_back( { tx, ty } );
        }
    }
    if( a[x1][y1] == ma ) {
        cout << "N";
        return 0;
    }
    cout << "Y\n";
    i = x1, j = y1;
    while( i - x2 || j - y2 )
        a1[i][j] = '+',
        i1 = dx[b[i][j]],
        j1 = dy[b[i][j]],
        i -= i1,
        j -= j1;
    a[x2][y2] = '@';
    for( i=0; i<n; ++i ) {
        for( j=0; j<n; ++j )
            cout << a1[i][j];
        cout << endl;
    }
}