foo.cc:9:1: error: expected unqualified-id before 'for'
 for(i = 2 ; int i<=sqrt(x);i++)
 ^~~
foo.cc:9:18: error: expected initializer before '<=' token
 for(i = 2 ; int i<=sqrt(x);i++)
                  ^~
foo.cc:9:28: error: 'i' does not name a type
 for(i = 2 ; int i<=sqrt(x);i++)
                            ^

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