Compilare: user.cpp: In function ‘int main()’: user.cpp:10:34: warning: too many arguments for format [-Wformat-extra-args] fprintf(g,"lld",(2+n*(n+1))/2); ^ user.cpp:9:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%lld",&n); ^