/in/foo.cc: In function 'int main()':
/in/foo.cc:16:8: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
       s+=a[i-1][j]+a[i][j-1]+a[i+1][j]+a[i][j+1]+a[i-1][j-1]+a[i-1][j+1]+a[i+1][j-1]+a[i+1][j+1];
       ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~