Pattern Matching Algorithm in C

#include<stdio.h>
int main(){
    char arr1[100], arr2[20];
    int l1, l2, i, count=0;
    printf("Enter first array: ");
    gets(arr1);
    printf("Enter Second array: ");
    gets(arr2);
    l1 = strlen(arr1);
    l2 = strlen(arr2);
    for(i=0;i<l1;i++){
        if(arr2[l2-1] == arr1[i+1]){
            count+=1;
        }
    }
    printf("%d\n", count);

    return 0;
}