View Compilation Error

0_0_33886338_17450.cpp: In function 'int main()':
0_0_33886338_17450.cpp:49:25: error: 'N' was not declared in this scope
     while(scanf("%d%d",&N,&M)!=EOF&&(N||M))
                         ^
0_0_33886338_17450.cpp:58:16: error: decrement of read-only variable 'M'
         while(M--)
                ^
0_0_33886338_17450.cpp:64:26: error: 'Union' was not declared in this scope
                 Union(x,y);
                          ^