View Compilation Error

0_0_30702598_11644.cpp: In function 'int main()':
0_0_30702598_11644.cpp:39:13: error: expected ';' before 'for'
             for(int i=0; i<2*n; i++)
             ^
0_0_30702598_11644.cpp:39:26: error: 'i' was not declared in this scope
             for(int i=0; i<2*n; i++)
                          ^