Backpacking

input/code.c: In function 'main':
input/code.c:17:5: error: 'res' undeclared (first use in this function)
   17 |     res = a+b;
      |     ^~~
input/code.c:17:5: note: each undeclared identifier is reported only once for each function it appears in
input/code.c:15:5: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |     scanf("%d %d", &a, &b);
      |     ^~~~~~~~~~~~~~~~~~~~~~

/******************************************************************************

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*******************************************************************************/

#include <stdio.h>

int main()
{
    
    int a, b;
    scanf("%d %d", &a, &b);
    
    res = a+b;
    
    return a+b;
}