View Compilation Error

0_0_9384290_29974.cpp: In function `int main()':
0_0_9384290_29974.cpp:4: error: `_int64' undeclared (first use this function)
0_0_9384290_29974.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_9384290_29974.cpp:4: error: expected `;' before "j"
0_0_9384290_29974.cpp:5: error: `n' undeclared (first use this function)
0_0_9384290_29974.cpp:8: error: `a' undeclared (first use this function)
0_0_9384290_29974.cpp:8: error: `b' undeclared (first use this function)
0_0_9384290_29974.cpp:9: error: `sum' undeclared (first use this function)
0_0_9384290_29974.cpp:10: error: `j' undeclared (first use this function)