View Compilation Error

0_0_18852667_21755.cpp: In function 'int main()':
0_0_18852667_21755.cpp:12:10: error: 'n' was not declared in this scope
     cin>>n;
          ^
0_0_18852667_21755.cpp:17:9: error: 'len' was not declared in this scope
         len=strlen(str);
         ^