Main.cc: In function 'int main()': Main.cc:5:10: error: 'm' was not declared in this scope cin>>m>>n; ^ Main.cc:6:23: error: expected ';' before ')' token for(int i=m;n<=i++){ ^ Main.cc:4:9: warning: unused variable 'mn' [-Wunused-variable] int mn,n,sum; ^