rez.cpp: In function `int main()': rez.cpp:13: `i' undeclared (first use this function) rez.cpp:13: (Each undeclared identifier is reported only once for each function it appears in.) rez.cpp:14: `n' undeclared (first use this function) rez.cpp:19: `sum' undeclared (first use this function) rez.cpp:20: `prod' undeclared (first use this function)