/in/foo.cc: In function 'int main()':
/in/foo.cc:24:16: warning: statement has no effect [-Wunused-value]
      {a[i][j+1]==0;
       ~~~~~~~~~^~~
/in/foo.cc:25:13: warning: statement has no effect [-Wunused-value]
    a[i][j-1]==0;
    ~~~~~~~~~^~~
/in/foo.cc:26:13: warning: statement has no effect [-Wunused-value]
    a[i+1][j]==0;
    ~~~~~~~~~^~~
/in/foo.cc:27:13: warning: statement has no effect [-Wunused-value]
    a[i-1][j]==0;
    ~~~~~~~~~^~~
/in/foo.cc:28:11: warning: statement has no effect [-Wunused-value]
    a[i][j]==0;
    ~~~~~~~^~~