class Solution {
public:
    int islandPerimeter(vector<vector<int>>& grid) {
        if (grid.empty())
            return 0;
        int m = grid.size();
        int n = grid[0].size();
        int prm=0;
        for (int ii=0;ii<m;++ii) {
            for (int jj=0;jj<n;++jj) {

                if (ii==0||ii==m-1) {
                    prm++;
                }
                if (ii>0&&ii<m) {
                    if (grid[ii-1][jj]!=1)
                        prm++;
                }
                if (jj==0||jj==n-1) {
                    prm++;
                }
                if (jj>0&&jj<n) {
                    if (grid[ii][jj-1]!=1)
                        prm++;
                }
            }
        }
        return prm;
    }
};