P1047

#include<stdio.h>
int main()
{
    int i, sum = 0, a, b, c;
    scanf("%d", &i);
    int lenth[i];
    for(a = 0; a <= i; a++){
        lenth[a] = 1;
    }

    int n;
    scanf("%d", &n);
    int start[n], end[n];
    for(b = 1;b <= n; b++){
        scanf("%d %d",&start[b], &end[b]);
    }
    for(b = 1; b <= n; b++){
    
        for(c = 1;c <= i; c++){
            if(c >= start[b] && c <= end[b]){
                lenth[c] = 0;
            }
        } 
    }
    for(a = 0; a <= i; a++){
        sum = sum + lenth[a];
        print
    }
    printf("%d",sum);
    return 0;
}