View Compilation Error

0_0_15856505_32261.cpp:3:11: error: '::main' must return 'int'
 void main()
           ^
0_0_15856505_32261.cpp: In function 'int main()':
0_0_15856505_32261.cpp:8:18: error: 'setw' was not declared in this scope
 cout<<setw(36-3*i)<<" ";
                  ^
0_0_15856505_32261.cpp: In function 'int main()':
0_0_15856505_32261.cpp:17:5: error: redefinition of 'int main()'
 int main(){
     ^
0_0_15856505_32261.cpp:3:6: note: 'int main()' previously defined here
 void main()
      ^