View Compilation Error

0_0_31715661_32689.cpp: In function 'int main()':
0_0_31715661_32689.cpp:6:15: error: 'n' was not declared in this scope
   scanf("%d",&n); 
               ^
0_0_31715661_32689.cpp: In function 'int main()':
0_0_31715661_32689.cpp:20:5: error: redefinition of 'int main()'
 int main() 
     ^
0_0_31715661_32689.cpp:2:5: note: 'int main()' previously defined here
 int main() 
     ^