foo.c: In function 'main':
foo.c:6:22: error: 'c\U0000ff0c' undeclared (first use in this function)
    6 | scanf("%d%c%d", &a, &c，&b);
      |                      ^~~
foo.c:6:22: note: each undeclared identifier is reported only once for each function it appears in
foo.c:9:1: error: expected '}' before 'else'
    9 | else if (c == '-') {
      | ^~~~

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