foo.cc:9:10: error: stray '\' in program
   sum+i: \\sum=sum+i;
          ^
foo.cc:9:11: error: stray '\' in program
   sum+i: \\sum=sum+i;
           ^
foo.cc: In function 'int main()':
foo.cc:9:8: error: found ':' in nested-name-specifier, expected '::'
   sum+i: \\sum=sum+i;
        ^
foo.cc:9:7: error: 'i' is not a class, namespace, or enumeration
   sum+i: \\sum=sum+i;
       ^

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