[dp function] stack overflow error

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define MAX 10
#define in "in.txt"
#define out "out.txt"
void split(char s[], char s1[], char s2[])
{
        int l, m;
                int i,j;
        l = strlen(s);
        m = l/2;
        for (i = 0; i < m; ++i)
        {
                s1[i] = s[i];
                //s2[i] = s[l - m + i]; // can't use to split s2
        }
                s1[i] = '\0';
                for (i = m; i < l; ++i)
        {
                s2[i-m] = s[i];
        }
                s2[i-m] = '\0';
}
int numofA(char s[])
{
        int count;
        count = 0;
        for (int i = 0; i < strlen(s); ++i)
        {
                if(s[i] == 'A')
                        count++;
        }
        return count;
}
int max(int x, int y)
{
        int result;
        if(x > y)
                result = x;
        else
                result = y;
        return result;
}
int hash(char s[])
{
        int result;
        char s1[MAX], s2[MAX];
        result = numofA(s);
        if(strlen(s) > 1)
        {
                split(s,s1,s2);
                result += max(hash(s1),hash(s2));
        }
        return result;
}
int dp(int v, int a, int e)
{
    int n;
    int result = 0;
    int a1,e1,v1,a2,e2,v2;
    n = a+e;
    for (a1 = 0; a1 <= a; ++a1)
    {
        a2 = a - a1;
        e2 = n/2-a2;
        e1 = e - e2;
        for (v1 = 0; v1 <= v-a; ++v1)
        {
            for (v2 = 0; v2 < v-a; ++v2)
            {
                if (max(v1,v2) == v-a)
                {
                    result+=dp(v1,a1,e1)*dp(v2,a2,e2);
                }
            }
        }
    }
    return result;
}
void writefile(int res, int ndp)
{
        FILE *f;
        f = fopen(out,"wt");
        if(f==NULL)
        {
                printf("Khong tao duoc file\n");
                exit(0);
        }
        fprintf(f, "%d\n", res);
        fclose(f);
}
void readfile2handle()
{
        FILE *f;
        int n;
        int a,e,v;
        int result;
        f = fopen(in,"rt");
        if(f==NULL)
        {
                printf("Khong doc duoc file\n");
                exit(0);
        }
        fscanf(f,"%d",&n); // not scanf \n and backspace
        for (int i = 0; i < n; ++i)
        {
                fscanf(f, "%d\l", &a);
                fscanf(f, "%d\l", &e);
                fscanf(f, "%d\l", &v);
                result = dp(v,a,e);
                writefile(result,n);
        }
        fclose(f);
}
int main(int argc, char const *argv[])
{
        readfile2handle();
        //printf("%d\n", dp(4,2,8));
        system("pause");
        return 0;
}