#include <stdio.h> int main() { int day = 0; int sum = 0; int coin = 1; int count = 0; scanf("%d", &day); for (int i = 1; i <= day;i++ ) {//用来计算天数 sum += coin; count++; if (count == coin) { coin++; count = 0; } } printf("%d", sum); return 0; }