View Compilation Error

2_16309_1138965_22999.cpp: In function `int main()':
2_16309_1138965_22999.cpp:20: error: `sum' undeclared (first use this function)
2_16309_1138965_22999.cpp:20: error: (Each undeclared identifier is reported only once for each function it appears in.)
2_16309_1138965_22999.cpp:24: error: `h' undeclared (first use this function)