foo.cc: In function 'int main()':
foo.cc:8:2: error: 'b' was not declared in this scope
  b=x/10%10;
  ^
foo.cc:9:2: error: 'c' was not declared in this scope
  c=x%10;
  ^
foo.cc:5:12: warning: unused variable 'z' [-Wunused-variable]
  int a,x,y,z;
            ^

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