View Compilation Error

0_0_9496854_357.cpp:3: error: `_int64' does not name a type
0_0_9496854_357.cpp: In function `int main()':
0_0_9496854_357.cpp:8: error: `_int64' undeclared (first use this function)
0_0_9496854_357.cpp:8: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_9496854_357.cpp:8: error: expected `;' before "a"
0_0_9496854_357.cpp:11: error: `a' undeclared (first use this function)
0_0_9496854_357.cpp:24: error: `factorical' undeclared (first use this function)
0_0_9496854_357.cpp: At global scope:
0_0_9496854_357.cpp:30: error: `_int64' does not name a type