2665 Trees 水题

#include "stdio.h"
int main()
{
//freopen("in.txt","r",stdin);
int l,m;
int i;
int sum;
int start,end;
while(scanf("%d%d",&l,&m) && (m!=0))
{
sum=0;
for(i=0;i<m;i++)
{
scanf("%d%d",&start,&end);
sum+=end-start+1;
}
printf("%d/n",l+1-sum);
}
return 0;
}