View Compilation Error

0_0_3186683_20717.cpp:11: error: variable or field `sum' declared void
0_0_3186683_20717.cpp:11: error: expected `)' before "n"
0_0_3186683_20717.cpp:11: error: expected `)' before "m"
0_0_3186683_20717.cpp:12: error: initializer expression list treated as compound expression
0_0_3186683_20717.cpp:12: error: invalid conversion from `time_t (*)(time_t*)' to `int'
0_0_3186683_20717.cpp:12: error: expected `,' or `;' before '{' token
0_0_3186683_20717.cpp: In function `int main()':
0_0_3186683_20717.cpp:25: error: expected `;' before "a"
0_0_3186683_20717.cpp:26: error: `a' undeclared (first use this function)
0_0_3186683_20717.cpp:26: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_3186683_20717.cpp:27: error: `b' undeclared (first use this function)
0_0_3186683_20717.cpp:28: error: `sum' cannot be used as a function