I am trying to read data, sort it, so I can determine peak values of a data set

I am trying to read data from a file that contains ECG data. I have the file being open and all the numbers being stored into an array. I have a while statement to keep it running while I have data in the file. I am trying to get the code to read that data into one array and then sort them into another array. Whenever I do this it doesn't give me any errors but the command prompt comes up with nothing in it and it doesn't terminate. Am I storing into the other array wrong?

#include<stdio.h>

int main()
{
    int X[128];
    int R[128];
    int S[128];
    int peak;
    int i = 0;

    FILE*fp_read= NULL;
    fp_read = fopen("ECG_data_128Hz_C.txt","r");

    while(i<128)
    {
        fscanf(fp_read, "%dC", &X[i]);
        //printf("%d\n",X[i]);

       if(X[i]>110)
        {
           scanf("%d",&R[i]);
           printf("R-Wave:%d\n",R[i]);
           break;
        }
        else if(X[i]<-50)
        {
            scanf("%d",&S[i]);
            printf("S-Wave: %d\n");
            break;
        }
        //peak = R[i] - S[i];
        //printf("Time between: %d\n",peak);

        i++;
    }
}