string concatenation by strcat()

#include <stdio.h>
#include <conio.h>
#include <string.h>

main()

{
    char s1[20],s2[20];

    printf("\n enter first string");

    gets(s1);

    printf("\n enter second string");

    gets(s2);

    strcat(s1,s2);

    printf("\n The concatenated string is %s",s1);

    getch();
}