View Compilation Error

0_0_7085123_25565.cpp: In function `int main()':
0_0_7085123_25565.cpp:6: error: `cin' undeclared (first use this function)
0_0_7085123_25565.cpp:6: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_7085123_25565.cpp:8: error: `cout' undeclared (first use this function)
0_0_7085123_25565.cpp:8: error: `endl' undeclared (first use this function)
0_0_7085123_25565.cpp:9: error: `xsum' undeclared (first use this function)