命令行号添加程序产生错误的结果

My Code:

#include <stdio.h>

int main(int argc, char*argv[]){
  int n = argc;
  int i, a, b, sum;

  for(i = 0; i < n; i++){
    sscanf(argv[i], "%u", &a);
    b = a + sum;
    sum = b;
  }

  printf("%d\n", sum);

  return 0;
}
#include <stdio.h>

int main(int arg