#include<iostream> using namespace std; int main() { int sum,day,dayall=1,dayalll=0,money;//dayall:第x+1~x+n天的n天；dayalll:天数总和 cin>>day; while(dayalll<day) { dayalll+=dayall; for(int i=1;i<=dayall;i++) { money+=dayall; } dayall++; } money-=(dayalll-day)*dayall; cout<<money; return 0; }