#include <stdio.h>#include <stdlib.h>int main(){printf("Please input n:");int n,x;scanf("%d",&n);if(n>=1){x=Sum(n);printf ("sum=%d\n",x);}elseprintf ("data error!\n");return 0;}int Sum(int n);{int sum=0,i,m;do{sum+=i;i++;}while (i<=n);m=sum;return m;}