Merge Sort and Binary Search

#include <stdio.h>
int na,nb;
void mergeSort(int c[], int low, int mid, int high);
void input(int a[],int b[])
{
        int i;
        printf("Enter the limit of A: ");
        scanf("%d",&na);
        printf("Enter the limit of B: ");
        scanf("%d", &nb);
        printf("Enter %d elements of A:-\n", na);
        for(i=0; i<na; i++)
                scanf("%d", &a[i]);
        printf("Enter %d elements of B:-\n", nb);
        for(i=0; i<nb; i++)
                scanf("%d", &b[i]);
}
void merge(int a[], int b[], int c[])
{
        int i,j = 0;
        for(i=0; i<na; i++)
                c[i] = a[i];
        for (i; i<(na+nb); i++)
                c[i] = b[j++];
        printf("The unsorted array is:\t");
        for(i=0; i<(na+nb); i++)
                printf("%d ", c[i]);

}
void partition(int c[], int low, int high)
{
        int mid;
        if(low < high)
        {
                mid = (low + high)/2;
                partition(c, low, mid);
                partition(c,(mid+1), high);
                mergeSort(c, low, mid, high);
        }
}
void mergeSort(int c[], int low, int mid, int high)
{
        int i = low, l = low, m = mid + 1, k, temp[200];
        while ((l <= mid) && (m <= high))
        {
                if(c[l] <= c[m])
                {
                        temp[i] = c[l];
                        l++;
                }
                else
                {
                        temp[i] = c[m];
                        m++;
                }
                i++;
        }
        if( l > mid)
        {
                for (k = m; k <= high; k++)
                {
                        temp[i] = c[k];
                        i++;
                }
        }
        else
        {
                for(k = l;k <= mid; k++)
                {
                        temp[i] = c[k];
                        i++;
                }
        }
        for (k = low; k <= high; k++)
                c[k] = temp[k];
}
void display(int c[])
{
        int i;
        printf("\nThe sorted array is:\t");
        for(i = 0; i < (na+nb); i++)
                printf("%d ", c[i]);
}
void search(int c[])
{
        int left = 0, right = (na + nb - 1), mid, key, found = 0;
        printf("\nEnter the element you want to find: ");
        scanf("%d",&key);
        while(left <= right)
        {
                mid = (left + right)/2;
                if(key == c[mid])
                {
                        found = 1;
                        break;
                }
                else if(key < c[mid])
                        right = mid - 1;
                else
                        left = mid + 1;
        }
        if (found == 1)
                printf("\n%d is found! It is at position %d.",key, mid);
        else
                printf("\n%d is not found in the array!", key);
}
int main()
{
        int a[100],b[200],c[200];
        input(a, b);
        merge(a, b, c);
        partition(c, 0, (na+nb-1));
        display(c);
        search(c);
}

//Output
//Enter the limit of A: 3
//Enter the limit of B: 3
//Enter 3 elements of A:-
//3
//2
//1
//Enter 3 elements of B:-
//6
//5
//4
//The unsorted array is:  3 2 1 6 5 4
//The sorted array is:    1 2 3 4 5 6
//Enter the element you want to find: 4
//
//4 is found! It is at position 3.