prog.cpp: In function ‘int main()’:
prog.cpp:15:10: error: call of overloaded ‘f(int, int)’ is ambiguous
f(10, 20);
^
prog.cpp:4:5: note: candidate: ‘int f(int, int, int)’
int f(int a, int b, int c = 10)
^
prog.cpp:9:5: note: candidate: ‘int f(int, int)’
int f(int a, int b)
^