ABC281B字符串格式判断标记

#include <stdio.h>
int n, m, i, j, k;
char s[15];
int main(){
    scanf("%s", &s);
    if(s[0]<'A' || s[0]>'Z') m = 1;
    if(s[7]<'A' || s[7]>'Z') m = 1;//头尾大写字母
    for(i=1; i<=6; i++){
        if(s[i]<'0' || s[i]>'9') m = 1;
        n = n*10 + s[i] - 48;
    }//中间6位数字不小于1000000
    if(n<100000 || n>999999) m = 1;
    if(s[8]) m = 1;//8位字符
    if(m) printf("No\n");
    else printf("Yes\n");
    return 0;
}