Main.cc: In function ‘void f(int)’:
Main.cc:6:10: warning: statement has no effect [-Wunused-value]
1;
^
Main.cc:8:10: warning: statement has no effect [-Wunused-value]
1;
^
Main.cc:10:12: error: invalid operands of types ‘void’ and ‘void’ to binary ‘operator+’
f(n-1)+f(n-2);
~~~~~~^~~~~~~