#include"stdio.h"unsigned jisuan(unsigned n,unsigned m){if(n>m)return 0;return n+jisuan(n+1,m);}int main(){unsigned n,m;printf("输入自然数 n,m:\n");scanf("%d%d",&n,&m);printf("n到m的自然数之和=%u",jisuan(n,m));return 0;}