how to solve error "stack around variable was corrupted" ?

Question

Hi, i got error in c program. the program is on arithmatic operation, in this output displaying properly, but when i press enter after seeing output then it will show me error like "stack around variable ch was corrupted"

 

below is my sample code

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

void Add(int x,int y)
{
    printf("%d",x+y);
}

void main()
{
    int a;
    int b;
    char ch;
    scanf("%d",&a);

    scanf("%s",&ch);

    scanf("%d",&b);


    switch (ch)
    {
    case '+':
        Add(a,b);
        break;

    }

    getch();
}

so help me how can i solve this ?