View Compilation Error

0_0_18357709_9982.cpp: In function 'int main()':
0_0_18357709_9982.cpp:13:12: error: 'n' was not declared in this scope
       time=n/(u-d)*2+1;
            ^
0_0_18357709_9982.cpp:13:15: error: 'u' was not declared in this scope
       time=n/(u-d)*2+1;
               ^
0_0_18357709_9982.cpp:13:17: error: 'd' was not declared in this scope
       time=n/(u-d)*2+1;
                 ^