foo.c: In function 'main':
foo.c:5:9: warning: statement with no effect [-Wunused-value]
    5 |         scanf
      |         ^~~~~
foo.c:5:14: error: expected ';' before 'printf'
    5 |         scanf
      |              ^
      |              ;
    6 |     printf("hello, world\n");
      |     ~~~~~~    
foo.c:4:13: warning: unused variable 'a' [-Wunused-variable]
    4 | {       int a=0;
      |             ^

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