View Compilation Error

0_0_19445323_26807.cpp: In function 'int main()':
0_0_19445323_26807.cpp:34:5: error: redefinition of 'int main()'
 int main()
     ^
0_0_19445323_26807.cpp:3:5: note: 'int main()' previously defined here
 int main()
     ^
0_0_19445323_26807.cpp:48:27: error: 'pow' was not declared in this scope
   printf("%d",(int)pow(2,i));
                           ^