foo.c:4:5: error: variably modified 'a' at file scope
 int a[n];
     ^
foo.c:5:1: error: expected identifier or '(' before 'for'
 for(i=0;i<n-m;i++)a[i]=a[i+m];
 ^~~
foo.c:5:10: error: expected '=', ',', ';', 'asm' or '__attribute__' before '<' token
 for(i=0;i<n-m;i++)a[i]=a[i+m];
          ^
foo.c:5:16: error: expected '=', ',', ';', 'asm' or '__attribute__' before '++' token
 for(i=0;i<n-m;i++)a[i]=a[i+m];
                ^~

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