View Compilation Error

769998_0_0_617.c: In function `main':
769998_0_0_617.c:6: error: `_int64' undeclared (first use in this function)
769998_0_0_617.c:6: error: (Each undeclared identifier is reported only once
769998_0_0_617.c:6: error: for each function it appears in.)
769998_0_0_617.c:6: error: syntax error before "sum"
769998_0_0_617.c:9: error: `sum' undeclared (first use in this function)