foo.c: In function 'main':
foo.c:5:10: error: 'b' undeclared (first use in this function)
    5 |  int a=0;b=0;c=0;t=0;
      |          ^
foo.c:5:10: note: each undeclared identifier is reported only once for each function it appears in
foo.c:5:14: error: 'c' undeclared (first use in this function)
    5 |  int a=0;b=0;c=0;t=0;
      |              ^
foo.c:5:18: error: 't' undeclared (first use in this function)
    5 |  int a=0;b=0;c=0;t=0;
      |                  ^

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