View Compilation Error

0_0_10182713_31258.cpp: In function `int main()':
0_0_10182713_31258.cpp:34: error: `ans' undeclared (first use this function)
0_0_10182713_31258.cpp:34: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_10182713_31258.cpp:38: error: `cin' undeclared (first use this function)
0_0_10182713_31258.cpp:43: error: `cout' undeclared (first use this function)
0_0_10182713_31258.cpp:43: error: `r' undeclared (first use this function)
0_0_10182713_31258.cpp:43: error: `endl' undeclared (first use this function)