为什么RE???

#include<cstdio>
#include<cstring>
using namespace std;
const int N=10007;
int l1,l2;
char s1[N],s2[N];
int main(){
    while((scanf("%s%s",s1,s2))!=EOF){
        l1=strlen(s1);l2=strlen(s2);
        if(l1>l2){
            printf("No\n");
            continue;
        }
        int i,j;
        for(i=0,j=0;i<=l1-1&&j<=l2-1;j++)
            if(s1[i]==s2[j])
                i++;
        if(i>=l1)
            printf("Yes\n");
        else
            printf("No\n");
    }
    return 0;
}