求m到n的和

#include<stdio.h>
int sum(int m,int n);
int main(){
int m1,n1,SUM;
printf("输入m和n的值（m小于等于n):");
scanf("%d%d",&m1,&n1);
SUM=sum(m1,n1);
printf("%d",SUM);
return 0;
}
int sum(int m,int n){
int result=0;
for(;m<=n;m++){
result=result+m;
}
return result;
}