View Compilation Error

0_0_6513955_15011.cpp:26: error: `__64' does not name a type
0_0_6513955_15011.cpp: In function `long long int sum(int)':
0_0_6513955_15011.cpp:45: error: `in' undeclared (first use this function)
0_0_6513955_15011.cpp:45: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6513955_15011.cpp: In function `void add(int, int)':
0_0_6513955_15011.cpp:60: error: `in' undeclared (first use this function)
0_0_6513955_15011.cpp: In function `int main()':
0_0_6513955_15011.cpp:74: error: `in' undeclared (first use this function)