foo.cc: In function ‘int main()’:
foo.cc:10:26: error: redeclaration of ‘int x’
   10 |     int n;cin>>n;int x,y,x;
      |                          ^
foo.cc:10:22: note: ‘int x’ previously declared here
   10 |     int n;cin>>n;int x,y,x;
      |                      ^
foo.cc:11:26: error: ‘z’ was not declared in this scope
   11 |         while(cin>>x>>y>>z,x) w[x][y]=z;
      |                          ^