View Compilation Error

0_0_17805325_28957.cpp: In function 'int main()':
0_0_17805325_28957.cpp:29:9: error: 'fo' was not declared in this scope
         fo+)
         ^
0_0_17805325_28957.cpp:29:12: error: expected primary-expression before ')' token
         fo+)
            ^