remove compile error

/home/user/gmapping_ws/src/openslam_gmapping/gridfastslam/gfs2rec.cpp: In member function ‘virtual void ResampleRecord::read(std::istream&)’:
/home/user/gmapping_ws/src/openslam_gmapping/gridfastslam/gfs2rec.cpp:148:17: error: redeclaration of ‘unsigned int i’
    unsigned int i;
                 ^
/home/user/gmapping_ws/src/openslam_gmapping/gridfastslam/gfs2rec.cpp:147:21: error: ‘unsigned int i’ previously declared here
   for (unsigned int i=0; i< dim; i++){
                     ^
make[2]: *** [CMakeFiles/gfs2rec.dir/gridfastslam/gfs2rec.cpp.o] Error 1
make[1]: *** [CMakeFiles/gfs2rec.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....

gridfastslam/gfs2rec.cpp

@@ -145,9 +145,9 @@ struct ResampleRecord: public Record{
 	virtual void read(istream& is){
 		is >> dim;
 		for (unsigned int i=0; i< dim; i++){
-			unsigned int i;
-			is >> i;
-			indexes.push_back(i);
+			unsigned int j;
+			is >> j;
+			indexes.push_back(j);
 		}
 	}
 };