/in/foo.cc:4:1: error: expected initializer before 'int'
 int x1,x2 x,i;
 ^~~
/in/foo.cc:5:1: error: expected unqualified-id before 'for'
 for(int x1=3;x1<=x12;x1=x1+2)
 ^~~
/in/foo.cc:5:14: error: 'x1' does not name a type
 for(int x1=3;x1<=x12;x1=x1+2)
              ^~
/in/foo.cc:5:22: error: 'x1' does not name a type
 for(int x1=3;x1<=x12;x1=x1+2)
                      ^~