View Compilation Error

0_0_30774095_25077.cpp: In function 'int main()':
0_0_30774095_25077.cpp:34:3: error: expected ';' before 'for'
   for(int i=0;i<2*n;i++){
   ^
0_0_30774095_25077.cpp:34:15: error: 'i' was not declared in this scope
   for(int i=0;i<2*n;i++){
               ^