#include<stdio.h>
main()
{
	char fin[100], fout[100];
	for(int t = 1 ; t <= 5 ; t++ )
	{
		sprintf(fin,".%d.in",t);
		sprintf(fout,".%d.out",t);
		freopen(fin,"r",stdin);
		freopen(fout,"w",stdout);
		int n, i, sum = 0;
		scanf("%d", &n);
        for( i=1 ; sum < n ; sum+=i++ );
        printf("%d", i-1);
    }
}