View Compilation Error

0_0_1832811_28608.cpp: In function `int main()':
0_0_1832811_28608.cpp:5: error: `_int64' undeclared (first use this function)
0_0_1832811_28608.cpp:5: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_1832811_28608.cpp:5: error: expected `;' before "n"
0_0_1832811_28608.cpp:11: error: `n' undeclared (first use this function)
0_0_1832811_28608.cpp:12: error: `i' undeclared (first use this function)
0_0_1832811_28608.cpp:12: error: `sum' undeclared (first use this function)
0_0_1832811_28608.cpp:17: error: `a' undeclared (first use this function)
0_0_1832811_28608.cpp:19: error: `fn' undeclared (first use this function)
0_0_1832811_28608.cpp:21: error: `s' undeclared (first use this function)
0_0_1832811_28608.cpp:33: error: `b' undeclared (first use this function)
0_0_1832811_28608.cpp:35: error: `c' undeclared (first use this function)