View Compilation Error

0_0_6306593_20643.cpp: In function `int main()':
0_0_6306593_20643.cpp:63: error: `pre' undeclared (first use this function)
0_0_6306593_20643.cpp:63: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6306593_20643.cpp:63: error: `cnt' undeclared (first use this function)
0_0_6306593_20643.cpp:66: error: ISO C++ forbids cast to non-reference type used as lvalue
0_0_6306593_20643.cpp:66: error: non-lvalue in assignment