View Compilation Error

0_0_34085950_6879.cpp:7:1: error: 'usingnamespace' does not name a type
 usingnamespace std;
 ^
0_0_34085950_6879.cpp: In function 'int main()':
0_0_34085950_6879.cpp:27:22: error: 'stringtem' was not declared in this scope
                      stringtem="";
                      ^
0_0_34085950_6879.cpp:31:22: error: 'tem' was not declared in this scope
                      tem=tem+str[i]+str[i+1];
                      ^