View Compilation Error

0_0_7098202_9029.cpp: In function `int main()':
0_0_7098202_9029.cpp:6: error: `sum1' undeclared (first use this function)
0_0_7098202_9029.cpp:6: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_7098202_9029.cpp:6: error: `sum2' undeclared (first use this function)
0_0_7098202_9029.cpp:6: error: `sum3' undeclared (first use this function)
0_0_7098202_9029.cpp:14: error: `sum' undeclared (first use this function)