a215: 明明愛數數 FYI: https://yunlinsong.blogspot.com/2015/09/blog-post_29.html

a215.cpp

#include <cmath>
#include <cstdio>

using namespace std;

int main(void){
	int n,m;
	
    while(scanf("%d %d", &n, &m) != EOF)
    {
		int sum = n;
		int cnt = 1;
		
		for(int t = n + 1; sum <= m; t++)
		{
			cnt ++;
			sum += t;
		}
		
		printf("%d\n", cnt);
    }

    return 0;
}